Hydroponic Pest Control: How to Protect Your Plants

When you’re using hydroponics to do your gardening, you don’t have the same risk of pest infestation that you do when outside. However, you probably still have some concerns about protecting your plants from pests. It’s a good thing to be vigilant, but it’s even better to prevent a pest problem before one happens. So here’s what you need to know about hydroponic pest control:

The most common pest problems in hydroponics

If you want to control pests, you first need to know what you could be dealing with. Here are some of the pests that you’re most likely to find if you’ve got pests in your system:


A lot of people are familiar with aphids from school lessons, and here you thought you were done with them. But they do infest hydroponic systems, especially when your plants have too much nitrogen in their food source. They’re usually found around the plant stems and these little guys can be either black, green, or grayish/tan.


Whiteflies can be tricky, but you can spot them pretty easily. They look like tiny white moths (about 1mm long), and fly away as soon as you’re about to catch one.

Spider Mites

Spider mites are even smaller than whiteflies, at under 1mm in length. And they’re definitely one of the most dreaded infestations of a hydroponic system. They do look like tiny spiders, but since they’re so small they can easily escape notice until an infestation gets way out of control.

Fungus Gnats

Fungus gnats are another tricky pest, since the grown gnat isn’t harmful but the larvae is. You’ll find the pest larvae eating at roots, which can bring on bacterial infections pretty quickly. 


Thrips, like aphids, can turn leaves yellow or brown because they suck the nutritients out. They’re a little bigger at 5mm, but still hard to spot. They’ll look like small, black dots on the upper sides of leaves.

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Avoid things that ‘invite’ pests into your growing area

There are certain ‘good practices’ that can help reduce the chances of a pest making its home in your hydroponic system. Fortunately, a lot of these practices involve a little know-how, and a bigger dose of avoidance. That means one of the best things you can do is avoid introducing opportunities that appeal to pests.

Don’t go in dirty

Before you enter your growing area, you should be wearing sterile (or at least clean) clothes. All kinds of bacteria, pests, and other contaminants can cling to our clothing totally unnoticed. Even if you don’t think there’s anything there, just don’t risk it. A pest problem is a high price to pay for skipping 2 minutes to get ready to enter your growing area.  You’re not done yet though, your tools and anything you bring into your growing area needs the same care.

Basically: don’t bring anything into your growing area that isn’t clean and contaminant free.

Give your system a sterile start

If you’re setting up your system, or doing a little work on it, see the tip above. Even fixtures, vents, tanks, and any other gear needs to be cleaned before they’re introduced into your growing area. Period.

Checking the quality of the seals around your growing area is important, too. While you want a well ventilated area, you don’t want a free for all for pests. Make sure there isn’t an issue with seals on windows and doors to outside areas (especially when your growing area is close to outside vegetation). 

Outside Materials

Pests can crop up from some sneaky places, and the materials you introduce into your hydroponic garden are an unassuming hiding place. The pest home that we inadvertently bring into our hydroponic systems?

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Growing medium.

Look, this isn’t to create a scare campaign because the truth is most growing mediums are perfectly sterile, and safe. But there are some things to look out for. If you’re getting an organic growing medium, such as coconut or rice husk, pay special attention. These mediums can harbor pests, so they need special treatment. Make sure that your growing medium has been sterilized, put through treatments to eliminate pests, and has some credible backing behind those claims.

New Transplants (take care)

Whenever you’re planning on adding transplants into your system, you need to be careful. Outside plants can carry bacteria, fungi, diseases, and pests. To combat these risks, you need to get any transplants from a clean, well maintained place you can trust. And before you go transplanting anything just because it came from a ‘reputable’ facility, take the time to examine the plants for any health issues.

The first steps in hydroponic pest control

Pest control can be something you start practicing with at the very start with your hydroponic system. Basically, putting in measures that deter pests is going to be your first line of defense. Here are the best ways to prevent a pest problem:

Watch your humidity

Some pests, like spider mites and fungus gnats, are especially attracted to low humidity and excess moisture in other parts of your system. Keeping your humidity from getting too low (50% is a good level to keep plants healthy and keep mites away), can prevent an infestation. But it isn’t all about your ambient environment. Keeping too much moisture from your growing medium can deter pests, like fungus gnats, from taking up residence (especially if you use rockwool, which they love).

How to identify a pest problem

Even with diligent prevention, you can still have a pest sneak its way into your system. Like any hydroponic set up, you should be examining your plants for problems regularly. That being said, you don’t want to confuse signs of pests with signs of other issues, such as nutrient deficiency or disease. Here’s how to tell if your plants are suffering from pests, or another ailment:


When pests suck the nutrients out of leaves (like aphids do), you’ll notice that the leaves become discolored and often turn a yellow color. This discoloration is centered around tiny holes that the pests feed from, not just generally spread on leaves.


Some pests can leave a signature pattern of spots, whether white, yellow, brown, or black.  If you notice spots, check to see if they’re deposits on the leaves (from eggs, feces, etc), or actual damage to the leaves. If the spots scrape off, you can pretty well bet you’ve got a pest issue.

When you notice these on any plant, check the leaves and stems of other plants to determine the pest and the degree of infestation.

Holes from pests vs burns and lesions:

When you first see a hole or rip, it can be easy to make assumptions. That’s why it’s important to look closer and check out the edges of any holes. Burns should be fairly obvious, as they’ll appear where light and heat sources are close to plants, and show discoloration around any holes or burns.

The pests that are most likely to infest hydroponic gardens are more ‘suckers’ than ‘munchers.’ That means the holes they leave from feeding on plants are tiny, and often raised and surrounded by a more yellow, or whitish area.

What to do when you have a pest?

If you’ve noticed some of the above symptoms of a pest problem, you need get it fixed and quickly. Unfortunately when a pest has already made its way in, it can be difficult to mitigate the issue.  Pests can run through a hydroponic system at a surprising speed, so once one plant is affected the others tend to follow in short order.

Don’t wait to take care of a pest.

If you act immediately after spotting pests, you may be able to spare the rest (or remaining unaffected) of your plants. If you wait, you’re probably going to come home to a garden that’s been almost, if not entirely, infested.

Determine the level of intervention needed:

Some pests can be taken care of by changes to the environment, manual removal, or other methods, while some pests can only be banished with chemicals. Whenever possible, avoid introducing harmful chemicals into your hydroponic system.

More gentle methods of pest removal:

Sticky traps

One of the first things you can do, depending on the pest you’re dealing with is use sticky traps. These work like the other sticky bug traps you’re familiar with, and can be really helpful especially with pests that have short life cycles. Another bonus of using sticky traps is that it can help you identify the pests infesting your system. If you can identify the pests, you can take a more appropriate route to getting rid of them (even if sticky traps don’t eliminate them).

Tip: Keeping sticky traps can be a preventative measure, too. If you see pests caught on a trap you can prevent a larger issue.

Natural solutions

A lot of solutions are marketed for killing pests, but you don’t want to chance killing your plants too. When in doubt, make sure your solution is backed with plant safe guarantees. A solution you can rely on, without a doubt, is Pyrethrin. It sounds very chemically intense, but don’t worry. It’s been given the green light for even certified organic farmers to use, so you know it’s safe. Pyrethrin is extracted from chrysanthemums, and can put a stop to pests.

A good spray down

Oftentimes you can give your plants a good hosing down to start getting pests under control. True, it won’t kill all your pests, but it can disrupt another cycle of reproducing, and it’ll get the bulk of them off your plants.

Hydroponic pest control: The cheat sheet

If you’ve found yourself with a pest problem that quickly becomes an emergency, here’s the cheat sheet you need.


  • Black spots on leaves – see Thrips
  • White or yellow spots – see Spider Mites, Whiteflies, Thrips, Aphids
  • Deformed stems or leaves – see Fungus Gnats, Aphids
  • Deposits on leaves – for silvery streaks see Thrips, small black see Thrips, sticky residue see Aphids, white masses and clumps see Mealybugs
  • Webbing around plants – see Spider Mites

Pest information and treatment


Aphids secrete honeydew, a sticky residue that stimulates the growth of sooty mold (honeydew can also attract other pests such as ants). These creatures such nutrients out of leaves and can leave them looking yellow and crinkled.

Tell-tale signs:

Aphids leave behind a good deposit of honeydew when they’re feeding, so you’re unlikely to miss these deposits. You can usually spot the aphids moving around stems, although they can be a variety of colors.


You can use predator bugs that feed on aphids to control their infestation; ladybugs and lacewings are the most common choices. Safe soap pesticides contain different formulations, but most are safe for plants and deadly for pests. Leaves, stems, or even whole plants that are severely infested may need to be removed. Next, try not to overfeed your plants, as that will increase aphid problems. 

Fungus Gnats

Adult fungus gnats are annoying but not a huge problem (aside from the fact that they reproduce). The larvae are going to be your real issue, as they congregate near and fed on the roots.

Tell-tale signs:

The first sign you may notice is the adult fungus gnats that fly up in masses whenever you disturb a nearby area. The larvae can be found by looking at the growing medium, and turning it over a bit. The plants they feed on start by looking ‘ill,’ meaning they get yellow leaves, look wilted, and seem frail.


First, avoid these guys by trying not to overwater your plants; but if you’ve already gotten to that point, try letting the growing medium dry out as much as possible, to a couple inches from the surface before adding any more moisture. You can catch eggs with sticky traps near the medium, and introduce nematodes to take care of the larvae. Neem oil can also be sprayed for severe infestations.


Mealybugs love fruiting plants, so if you’re growing the like you’re more likely to see them. These are another ‘sucker’ type of pest, so you’ll notice weak, yellow leaves if an infestation becomes larger.

Tell-tale signs:

Mealybugs leave eggs in white, cottony looking masses on the undersides of leaves and stems (although they make be located anywhere on the plants). They leave behind a honeydew residue, much like aphids, and generally have a waxy coating.


Solutions: you can treat Mealybug problems with a gentle, natural pesticide or insecticide. You can also use a solution of 1 oz Neem oil with 1 gallon of water and spray every 1 or 2 weeks until the infestation is gone. Some helpful insects such as ladybugs can also be used.

Tip: if you catch an infestation early, you can manually destroy egg sacks with a swab soaked in alcohol and then remove them.

Spider Mites

Spider mites leave fine webs all over plants, and can be a difficult pest. They tend to infest areas with high temperatures and low humidity.

Tell-tale signs:

First, the webs. Spider mites leave behind sticky webs, just like regular spiders, but smaller and finer. Since they also suck nutrients from leaves, you may notice yellow and whitish spots on leaves. They can grow in number quickly before you notice webs, so check the undersides of leaves where they gather.  


First, manually remove areas of high infestation by pruning and removing heavily infested leaves and stems. Then you can use a safe, organic insecticide or biological insecticide to get it under control. A mixture of Neem oil and a wetting agent (for better spread) can also be sprayed every few days to kill mites and eggs.


Thrips can grow huge populations in a short amount of time, and a heavy infestation can cripple a garden if left untreated. These hyper active pests are especially attracted to light colored plants and flowers.

Tell-tale signs:

One of the biggest signs that you’ve got a thrip problem is black spots on the leaves. The black spots are actually feces dropped onto leaves. You’ll also notice that the plants they feed on get discolored spots and may appear dry.


The first thing you can do to get rid of thrips is release some insects that feed on them. Lacewings and ladybugs are typical beneficial bugs, but minute pirate bugs are most effective when it comes to thrips. If the problem grows too large, pyrethrin can be used, and followed with an insecticidal soap when needed. 


Whiteflies hide on the undersides of leaves and look like miniature moths. Like fungus gnats, they fly up in large crowds when disturbed.

Tell-tale signs:

Like aphids, whiteflies leave a sticky honeydew residue that you can spot on leaves (as well as any sooty mold that’s grown as a result). You may also see light, discolored spots where whiteflies have been feeding on leaves. Once an adult population has been established, you should be able to easily tell if they’re in your system.


To begin reducing the infestation, spray plants with water at a moderate pressure, and begin introducing beneficial insects. Like most pests, you can use ladybugs and lacewings to reduce them, as well as the whitefly parasite. Organic soap insecticides can get rid of them quickly, as can spraying with Neem oil.

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How to Build a Deep Water Culture System

Deep water culture systems are among the most accessible and most cost-effective hydroponic systems any gardener can run. The materials required are straightforward, yet there are numerous ways these DWC systems can be built.

It is possible to purchase these systems, but because they are so easy to construct, it is worth any growers time to build one and use it as a learning tool for future projects. Here we will run through what exactly is DWC, the advantages, and disadvantages of this system type, and what it takes to build this type of hydroponic system.

Types of DWC Systems

There is the regular DWC system, and this is the one that we will focus on here. There are though a couple of other types which are worth mentioning. They are very similar in construction, but with a few minor differences.

Kratky Method

This in construction can be precisely the same as a regular DWC system apart from it not using an air pump. The entire system is passive and has no additional features or equipment.

The way this system works is to leave a gap between the surface of your nutrient mix and the roots. This will be a half-half situation where half of the roots are exposed, and the other half is submerged. As the water levels drop, the roots will grow longer and follow it down.

RDWC (Recirculating Deep Water Culture System)

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These recirculating DWC systems are used when there are scaling issues. Regular DWC systems can’t be scaled up efficiently. These work like a cross between DWC and flood and drain systems, but with one difference. The nutrients never drain away from the growing area.

This works by having several containers or buckets that are all connected to a central reservoir. This allows you to scale because it only requires additional buckets to be added. In practice, the oxygenated water passes from the reservoir to each plant in turn before returning back to the reservoir.

In each bucket, there will be sufficient growing space for around 2 or 3 plants depending on the variety. Also, if you have more than this, there may be contention for the nutrients and the oxygen between your plants.


This system is exactly the same as a regular DWC system, and the only difference being, the addition of a water pump. This sits inside the reservoir and pumps the oxygenated water to the top of the net cups where your plants are sitting.  This then runs through the growing medium and cascades back into the reservoir.

This type of bubbleponics system is ideal when plants are small, and their roots don’t reach the water in the reservoir. Once they are long enough and can reach the solution by themselves, this type of system holds no benefits over a regular DWC system.

Items Needed to Build a DWC System

  • Water and nutrient reservoir
  • DWC net pots for holding your plants
  • Hydroponics nutrients and pH adjusters
  • Air pump and air stones for tank aeration

Here are each of the components in a little more detail:

DWC Reservoir

In a DWC system, the plant roots will be suspended from above in the net pots. Their rooting systems will reach down to be immersed in the solution. There are systems of this type that can have reservoirs for each plant, or you have numerous plants sharing the same reservoir.

If plants share the same reservoir, it may be challenging to grow different plants together. Single plant reservoirs offer more flexibility and control.

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The reservoir can be any dark container which has a lid. In this, you will cut holes large enough to support your net pots. These pots will then be filled with growing medium.

It should be noted that no light should be allowed to get inside as this can lead to algae growth, and as the roots will be exposed, they could fall foul of air pruning if the light is there for extended periods.

When you install your air pump, the tubes should be changed to black rather than clear plastic, as this can aid algae growth which will spread further into the tank. You should also check where the lid sits on top of the tank, and if needed it can be sealed with plumbers tape.

One helpful tip that some growers do it to cover the top of the tank with a reflective material. This not only prevents ambient light heating the tank, but it also helps to reflect light back on the underside of your plants.

Net Pots for DWC

The difference between net pots and regular pots is they have no solid part, they are instead a mesh where the roots can easily travel to reach the solution that is underneath them. You can make your own net pots, but because these are so cheap, you are better sticking to net pots that you can purchase.

Your pots will also be the placeholder for your inert growing medium that has low water retention properties. Clay pebbles (Hydroton) are ideal for this as they allow maximum airflow to reach the roots. Before planting into these, you will need to germinate your seeds. These are more likely to be in Rockwool cubes which you can transfer once they are large enough.

Note: When you first transplant your seedlings, there is no way the roots will be long enough to reach the solution in the reservoir. For the first few days, you will need to top-water your plants.

Additionally, you can make sure your Rockwool cubes are touching the surface of the nutrient solution. This way they can wick the water up until the roots can take directly from the surface.

Hydroponic Nutrients

With a DWC system, you will need to keep an eye on your pH levels. The range should be between 5.5 and 6.5, with the ideal reading being 5.8. One advantage to a DWC system is you can actually use fewer nutrients than in other types of system, but all the while, you do need to carefully monitor the pH levels.

This is where your pH UP and your pH Down come into play.

One other thing to note is your EC/ ppm levels, as these will let you know the concentrations of your nutrients. This will be crucial when you are learning when to flush the system. When you understand your plant’s requirements, you may find you can go through an entire grow without changing the solution, and topping off the reservoir will only depend on the number of nutrients they are using.

DWC Aeration

Plants need oxygen to grow, and although they will receive some through the clay pebbles, it will not be enough to support them. Air pumps can be one of the most crucial elements of any DWC system. It is advisable to choose an air pump that has no less than 2 outlets. This will allow you to place air stones in separate parts of your reservoir to deliver plenty of oxygen.

The type of air pump you choose does need to deliver enough oxygen to the water. A good guide is one that can deliver double the liters per hour of the volume of your reservoir. This means if you have a tank which holds 100 liters, then you need an air pump which can supply 200 liters of air per hour.

It is worthy to note, this air pump will be running around the clock to keep your solution well-aerated. If it fails, then you can see your plants dying quickly.

If you wish to measure the amounts of oxygen in your water, you can purchase a dissolved oxygen meter. The better and more accurate ones are not cheap, and it should be enough to produce as much oxygen as you can rather than measuring the levels you think you have. These devices are more beneficial to commercial growers.

How Does DWC Work?

Plants don’t take too kindly to having their roots submerged in water, and can become suffocated. In a lot of cases, this will lead to death. But why is it different in a DWC system, as the plants have their roots submerged in water 24/7?

The key to their survival is oxygen. This is where the air pump comes into action because it delivers copious amounts of oxygen to the water. In other hydroponic systems, you can also use air pumps, or falling water in a circulating system can add oxygen to the water.

In DWC systems, the plants can take the dissolved oxygen from the water at the same time as they are soaking up the nutrients. This, in fact, helps them to grow much faster than they would if they were in the soil.

To your reservoir, you will add your water and nutrient mix, this will be pH adjusted into the ideal range. Once you have this, you will then have your plants suspended in the net pots which are protruding through the lid of the reservoir.

At this stage, you will be using the air pump, and when choosing the right air pump for your system, make sure you have one that has multiple nozzles. This will allow you to place more air stones, or you can use one pump for multiple reservoirs.

When the roots are long enough to reach the nutrient solution, then their growth can explode.

This works because in the soil, plants need to search out small water pockets, and in a DWC system, everything they need is right underneath them. You may think you have too many air bubbles, when in fact, the more you can have the better it is for your plants.

DWC Pros and Cons

To fully understand how these DWC systems work, it is good to see the pros and cons that come with them.


  • Faster plant growth because of the enhanced uptake of nutrients and oxygen in the water. A good example being lettuce. This can be grown in around 30-days compared to 60-days when grown in soil.
  • There are very few moving parts – in many cases, there is only the air pump
  • Because the roots are submerged in the nutrient mix, there aren’t as many nutrients or fertilizer required.
  • Once a DWC system is up and running, there is very little maintenance required. As there are few moving parts or circulating water, there is nothing that can become clogged or blocked

All isn’t rosy with DWC systems, and they do have some downsides. Luckily though, the upsides outweigh the bad points by quite a considerable amount.


  • In smaller DWC systems, it can be easy to calibrate your nutrients incorrectly, this can be in either direction.
  • Should you have a power outage or pump failure, it can be a matter of hours before your plants drown to low oxygen levels.
  • You can see wide fluctuations in your nutrient mixes. This can include water and pH levels.
  • It can be challenging to maintain an ideal temperature if you are using a none-circulating DWC system.

As you can see, the majority of problem areas come from the lack of air to the solution. If you can prepare for this, then this will reduce the risk of dying plants. Because of this, some growers have backup air pumps in case this happens.

Lighting for DWC Systems

This will depend on where you are running your DWC system. If you have access to sunlight, then the natural periods are more than sufficient. But, if you are growing indoors, this is very different as you need to take into consideration the heat your lighting will be generating.

Supplemental lighting should only be run for a maximum of 16 hours per day, because plants need time to rest, and 8 hours of darkness is more than enough.

You do need to consider the combined heat of any pumps and lighting, and the effect it has on your water temperature. It may be the case you need a small chiller unit if you are using HID lights. Depending on your plant type, you may be able to get away with T5 fluorescents as these run much cooler, and might not affect your water temperature too much.

Common Questions Asked About DWC Systems

Which Type of DWC Should I Try First?

If you are an absolute beginner, then it is probably better, to begin with, either a conventional DWC system or if you don’t want to commit straight away, you can try a Kratky system. These types are both straightforward to set up and inexpensive. Although they might appear the most simple in function, they can still deliver excellent yields.

What Nutrients Should I Use In My DWC System?

Many growers decide to use organic forms of nutrients, and while these do produce great results, it is advisable to stick to nutrients which are known to work and can be easily adjusted.

General Hydroponics 3-part set is more than ideal, and they can be easily adjusted to different ratios that will suit a wide range of plants. These are also relatively inexpensive and are well proven to work.

How Deep Should the Roots Go Into the Water?

When you are transplanting your seedlings or topping off your reservoir, you should make sure you only submerge the bare root into the water. The stem of your plants should remain exposed. There should be around 1.5 inches of roots that are outside of the surface of the water.

These exposed parts of the root system allow your plats to take up even more oxygen from the plants surroundings.

What Should the Temperature of My Reservoir Be?

As we saw, temperature can be one of the downsides to DWC systems. If you are growing indoors, and have a circulating system, then the pump will be generating heat as well as heat from your grow lights. If your nutrient mix becomes too warm, it reduces the amount of oxygen in the water. On the other hand, if you are cooling your mixture and it becomes too cold, it can cause plants to have stunted growth.

Surrounding air temperatures should be around 75 – 80F, and the temperatures around the root zone need to be in the range of 60 – 68F for optimum growth.

What Should the Ideal pH and EC/PPM Be For DWC?

The recommended range of the pH level is from 5.5 to 6.5. Although, this will depend on the plant type and the growth stage of your plants.

It is usual for vegetative crops to have pH levels that are in the higher end, while fruits or flowering plants will be requiring a pH level which is at the lower end.

When you start looking at the EC levels, it is advised you mix lower levels of nutrients in DWC systems. There are a couple of reasons for this. First, if your water is none circulating, the concentration is all in one place, and this is directly exposed to your plant’s roots.

Secondly, plants take up more water than they do nutrients so this will enrichen the nutrient content in your solution as levels drop, thus giving a higher EC level. If you add full strength, this can be more harmful to your plants. Adding lower levels won’t necessarily hurt them, it just means they will be working a little harder to absorb what they require.


A DWC system is very easy to set up, be it one that is purchased, or one which is built yourself. The results will be the same, and this is high yields from your plants with minimal effort. Another advantage of a DWC system is that it can be used as a supplemental system if you have spare space, they take so little effort to run that even the smallest of spaces can be used.

Anyone who wishes to try hydroponics is advised to try one of these systems first. There is nothing to lose, but as a grower, there is everything to gain.

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How to Set Up a Hydroponics System: The Fundamentals

Many people have either just started with a Hydroponic garden or are looking into starting one. Although there are vast amounts of information available, many sources don’t cater to new growers when it comes down to the fundamentals of running or building a hydroponic system.

There are many types of systems users can use, but these core fundamentals remain the same no matter which system is being used.

Here we will take a look at each section in turn and see how it reflects on your system, or how it can affect your decision on which system you wish to build. Before diving into the core fundamentals, we will give a rundown of the most common types of hydroponic systems people choose to run. These can be purchased or bought, and it doesn’t matter how the system is built, the end result will be the same.

Types of Hydroponic Systems

With all these systems, we will look at what they comprise without mentioning nutrients or pH kits because these will be standard across all systems.

Kratky System

Difficulty: Beginner

This is one of the simplest methods of hydroponics available and requires no electricity. All this needs is a dark container with a lid, net pots, and your growing media. These are suitable to grow spinach, lettuce, tomatoes and many other leafy types of vegetables.

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In the lid will be the holes where to place your net pots. Once they are filled with your growing media, the young roots will protrude from the bottom of the net pot into the solution. As they absorb nutrients, the level drops and the roots grow. At this point, the space in the top of the container delivers oxygen to the roots.

DWC (Deep Water Culture)

Difficulty: Beginner

A DWC system is very similar to the Kratky system but on a larger scale. This system only requires an aerator pump and can cater to a more significant number of plants. In this system, the water continually bubbles to deliver oxygen to the plant’s roots.

Flood and Drain (Ebb & Flow)

Difficulty: Intermediate

This is one of the most popular hydroponic systems in use, and for a good reason, it can produce some of the best results out all the systems while being easy to maintain. Here the plants will be grown in any suitable growing media inside pots. These are then spaced in a grow bed which is a little higher around the sides than the containers.

The nutrient reservoir will be a separate unit that is large enough to hold enough nutrient solution to flood the grow bed. In the grow bed, there is an overflow pipe that will stop water rising above the height of the pots. Next, you will need a water pump which is used at intervals to flood the grow bed, once the timer finishes (15 or 30 minutes at intervals) the water flows back through the pump into the reservoir.

Plants receive enough water, and oxygen once the grow bed drains. The addition of air stones will deliver more oxygen to the roots which lead to healthier plants.

NFT (Nutrient Film Technique)

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Difficulty: Advanced

These systems are an all in one solution. In most cases they contain large 4-inch PVC pipes that have holes cut into them which will hold your net pots, again these are filled with your growing media, and the roots protrude into the bottom of the pipe.

The reservoir will hold the pump and air stones, which continually flows down the pipes and returns back to the reservoir. Roots are still exposed to the air to receive oxygen so they won’t become overwatered. The weak area of this is when there is a pump failure. Plants can quickly suffer because their growing medium won’t be holding sufficient moisture to maintain the plants for extended periods.

Drip Systems

Difficulty: Intermediate

In this system, each plant will be fed individually. What differs in this kind of system is the plants are drip fed from above whereas all other systems are fed from below. There is still a separate reservoir that contains both the water pump and aerator stone, and from the pump, there are small diameter tubes that feed the pots on a timed period. The nutrient then drips from the bottom of the pot or container back to the reservoir.

In design, it is very similar to a flood and drain system, but without the flooding aspect.

There is one other system called aeroponics which differs to all of these because a fine mist of nutrients is sprayed onto the roots. These can be much harder to set up, and might not deliver as many plants in your growing space. Additionally, many of these systems are purchased rather than being built.


A Look at Hydroponic Fundamentals

We will now take a look at the fundamentals of hydroponics. These will contain seen before information and will be general across all systems.

There might be problems with one system more than another, but the ways to solve these will be the same. As an example, if you have waterlogged roots, then the solution will be the same regardless of the system. All that differs in hydroponic systems is the nutrient delivery method and the ease of operation.


Germination requires very different rules when it comes to growing in a hydroponic system so they will have their own section. But, once plants are transplanted, they do light which is the most essential ingredient for plant growth.

It doesn’t matter if you have your system in an outdoor location, or an indoor grow room, without light, and sufficient amounts of it, your plants won’t survive. The purpose of light is to induce photosynthesis where carbon dioxide and water become converted into plant food and oxygen. So, the more light your plants receive, the faster and more bountiful they will grow.

There is one worthy mention, and that is if growing indoors under artificial light, you can obtain better results than if plants were being grown in a sunny window. This is because you are controlling the amount of light compared to variable light throughout the day.

Sunlight varies throughout the year, so even if your plants are in a warm enough environment, their growth will still change throughout the seasons.

When using grow lights, the one thing you must ensure is plants receive the full spectrum of light. This needs to be from the bluer end of the spectrum all the way to the other where there is an abundance of red light.

When using grow lights, there are countless types and strengths that growers choose. You can choose from fluorescent, LED’s, High-pressure sodium or metal halide bulbs. All these come with unique benefits and downsides.

What is crucial is that no matter which bulb you use, they all governed by the following three factors:

CCT (Correlated Color Temperature)

This is expressed by using a Kelvin scale and will relate to the temperature of the light source. This doesn’t necessarily mean one bulb is hotter than the other to the touch. It is the warmth of light that is measured.

A good example is 6000 Kelvin is recognized as being cool light, and a light source which has a CCT (Kelvin) of 2700 would be considered warm.


A grow lights watt usage is how much energy it will use when it is turned on. This also has a relation to how bright it will be because of the electric running through the element.

A regular light bulb in the home uses about 75 watts. But, in some hydroponic grow rooms, there are lights of 250, 600 up to a 1,000-watt bulb being used. At this level, they will use the same electricity as you’re A/C or other larger electrical device.

The downside to most of these HID lamps is they need changing periodically:

  • 24 hours per day – change after 6 months
  • 18 hours per day – change after 9 months
  • 12 hours per day – change annually


This is how much light per square foot that will be emitted by your grow light bulbs. This measure will be dictated by the manufacturer and not the power consumption (wattage). High numbers of lumens equate to high-quality lights. Never opt for a bulb which delivers less than 2,500 lumens. You can also use the 20 – 50 watts calculation for each square foot of your growing area.

With all this, it is fundamental that you provide your plants with at least 14 – 16 hours of good light each day.


There are a few factors that are included under air, these will be humidity, temperature and carbon dioxide. All these are important for any hydroponic system and can have a severe impact if they are not in the right region, or the correct levels are not met.

Carbon dioxide is produced by every breath we exhale, and to a certain extent, there are levels in the air we breathe in. In outdoor gardens, these levels are controlled without too much intervention, but for an indoor garden, this can be very different.

Air ventilation, rather than only having airflow is crucial because the levels of CO2 might only reach around 400 ppm (parts per million). Levels required should be up to approximately 1,500 ppm, and without supplementing this unnaturally, it will need fresh air to be entering your grow room.

You can see how some growers control this by using grow tents, this reduces the space, so the ppm of CO2 increases. These tents will have an exhaust fan, and fan on the other side which blows in the fresh air.

After this, we come to the ambient temperature. This can change depending on your plants. However, almost all plants are unable to survive for too long outside their ideal growing temperatures. This can be either up or down, so growers shouldn’t think just because they are indoors that it doesn’t become too cold.

This is another area that is affected by an influx of fresh air from a ventilation system, and also from any grow lights which are in operation. The ambient temperature of the air does need careful monitoring and adjustment.

The next area affected by the air is humidity. Some plants are very choosy about humidity levels. When humidity is too high, it becomes ideal for mold or algae, and this is especially true in your reservoir. Low humidity on the other end, can stress plants as it struggles to replace moisture.

Water and Hydroponic Nutrients

Every system has different requirements. These can be because of the grower or the plants being grown. Many growers choose already mixed nutrients, and merely adding these in varying quantities is enough for many people.

There is though, an underlying element to this which is fundamental for successful growth which growers should be aware of. Purchasing a bottle of nutrients is straightforward, but knowing what they do is very different.

Knowing how these elements work, it is handy to see how commercial growers use their powdered compounds to achieve their desired results.

NPK is what all grower know what they need to follow for maximum growth of their plants. These come in different solutions such as 20-10-5. This means there is 20% Nitrogen, 10% Phosphorous and 5% Potassium.

When plants reach later growth, they should be receiving lower amounts of N (Nitrogen), this is why some larger scale commercial growers mix their own, they are in a far better position to control each compound as necessary.

One thing to note here reflects back to the temperature of your grow room. You might need higher amounts on N (Nitrogen) if the temperature is under 80F when your plants are in their vegetative growth phases. If your grow room has a temperature that is higher than this 80F, then you don’t need to adjust the N levels.

There are lots of NPK ratios you can see, but not all will be right for your garden. Here is a guideline that can be used as a starting point:

N (Nitrogen) – 200 – 400, P (Phosphorous) – 200 – 600, and K (Potassium) 200 – 600

On occasion, plants might suffer from magnesium deficiency. The addition of Epsom salts to your water is an easy remedy for this. No matter how you obtain your nutrients, and this can be dry or liquid, but the one fundamental thing is to never over-feed your plants. It is much better to slightly underfeed and add rather trying to reduce.

When we look at nutrients and water, there is the temperature to consider, and if your mix is too warm, this can lead to bacterial growth. Other areas which need consideration and are fundamental to successful plant growth are:

  • EC (Electric Conductivity)
  • CF (Conductivity Factor)
  • TDS (Total Dissolved Salts)
  • pH Levels

When you look at your TDS levels, these are ideal when they fall in the range of 500 – 1000ppm in your solution. When there is a reduction in the ppm plants can take up nutrients easier. This is true in younger plants or seedlings, and once they reach their vegetative growth phase, these levels can be increased to 800 – 900ppm. This will equate to a stronger nutrient solution.

Once plants reach their maturity or flowering phase, these TDS levels can be further increased to 1000ppm – 1100ppm before being reduced in the final phase.

No matter what levels you are using, these TDS levels should be measured along with pH levels on a continual basis. EC meters test the conductivity of your solution and will determine the TDS which is the level of dissolved salts.

We all know pH levels need to be measured on a routine basis. These work in conjunction with the strength of your solution because they will change as you add nutrients, or add new water to your reservoir. Ignoring these or leaving them too long before checking can have a dramatic effect on your plants.

One fundamental factor is to never mix either pH UP, or pH Down into your nutrient mix. The chemical components can produce a chemical reaction. Such is the risk of this, you should only use one dropper for each chemical. Water should be checked adjusted before it is added to your reservoir, this way you can adjust without shocking your plants with a dramatic rise or fall of the pH level.

To make sure your nutrients don’t become too strong, you can top up (top off) your reservoir with half strength of nutrients to what you first began with. This should be done every other day, and the days in between, you can top up with plain water (pH checked).

Changing Nutrients and Flushing Reservoir

This will be one of the most fundamental things a grower needs to do for their system. But, there are two ways that different growers use to calculate when to do this. One uses a time-based approach, and the second uses the volume-based approach. This is where the above TDS levels come into play.

Here are the two different approaches to doing this:


This can be between 10 – 14 days for small hydroponic systems. It required all of your old nutrient mixes to be disposed of and refilled with a new solution. Larger systems can be stretched to one month before changing the solution. Out of the two, this is the recommended way of gauging when to change.

Volume-based flushing

Using the above TDS and EC readings, the time to flush the system is when youhave used half the starting amount. With this way, many people top off their tanks as nutrients are absorbed. This requires continual monitoring, as soon as the top off amount reaches half of the original starting volume, then it is time to flush the system.

Growing Mediums and Water Quality

A growing medium adds nothing to a hydroponic system in the way of nutrients. There the only function is to deliver support for your plants. There are many of these growing mediums which are suitable, and on occasions, a grower will use more than one type.

Many growing mediums must be thoroughly soaked before use. This is the case for Rockwool when germinating, but also vital when used in a full system. It is crucial to use the best growing medium for the plants you grow and the type of system you are using. A good example being coco coir. In systems which utilize water pumps, the fibers can start blocking the pump, but in DWC or NFT they have less chance of easily being passed around your system.

When using water for your hydroponic system, this needs to be clean, so there are no bacterial elements contained in it. This is why growers use pure or reverse osmosis water. It also means they have a clean slate when it comes to adding their nutrients.

If you see deposit buildups around your faucets, this means you have hard water. If this is the case, it means you have too many minerals. If you use this kind of water and it has a TDS of over 200ppm, you will need to adjust to allow for this difference because it will affect your TDS with nutrients added. Again, this is the reason clean water is used.

We have seen it is crucial to keep your nutrient mix at a certain temperature. However, it should be noted that optimum root growth will happen when your mix is between 70 – 75F, but if you have any root diseases, these grow faster in these conditions.

If you maintain a temperature under 68F, it can go a long way to helping prevent root rot in your plants.

Additionally, it is harder to regulate the temperatures in both DWC and other ‘Bubbler’ systems because there isn’t usually an external reservoir and the small water volumes. One other point of note that is very often overlooked is that aquarium pumps can run hot, so they do add heat to your nutrient mix.

Fundamental Do’s and Don’ts for Your Hydroponics System

We know that there are some varieties of plants which don’t grow very well in hydroponic systems. Many root crops are not as successful as leafy vegetables because of the way growing media works compared to soil.

There are as we said many fundamentals which need adhering to, as well as a handful of things you should do, and things you shouldn’t. These can be seen here:


  • Light exposure to your reservoir should be limited to when you are topping off your solution. All pipes leading to growing beds should be dark to prevent light exposure and every possible way light can seep through your cover should be capped.
  • Clean supply and drain lines on a regular basis. This can be every few days depending on the type of system you use.
  • Pumps lose efficiency over time, check these to make sure they are pumping as they should. Flood and drain systems especially.
  • Clean filters if they begin clogging. Coco coir can cause blockages here.
  • If you use reusable growing media, wash it before re-use and allow it to dry.
  • Carry out thorough sterilization of media and pots and any other components between growing cycles.
  • Sanitize your components and system daily.
  • Do always check your pH levels. Even if you use a litmus strip for a quick check, you can quickly see if there are any changes.


  • Never use lemon juice
  • Never use liquid bleach in your system
  • Never add iron while any UV is running. This can lead to chelates being created. Any UV should be turned off until the system has cycled.
  • Don’t let your growing media remain wet, this will lead to root rot. Time your cycles, so the growing media is almost dry before the next feeding cycle.
  • Never use a water softener to treat hard water. These add salts to the water that are harmful to plants.
  • Don’t let your nutrient mix rise above 75F or fall below 50F. You might need an aquarium heater or chiller to compensate. Air stones can be used to help cooling as long as they are using external air.
  • Don’t place grow lights too close to your plants. If you have no option, point an oscillating fan to where the hottest areas will be.


As you can see, there are a few things you need to keep an eye on or consider when setting up a hydroponic system. With the basics of your water and nutrients, the effect of lighting, and ventilation, you will cover almost everything.

Some of this will depend on your grow space, and if you have access to external windows or it is sealed off, and you are wholly reliant on grow lights. Once you have these basic fundamentals under control, you are in a position to take on any hydroponic system because the same basic rules will be the same.

Once you learn the basics, you can quickly extend any system or build a larger one from scratch. A lot of the fun is in discovering new tips and techniques, but these fundamentals will never change.

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How To Germinate Seeds For Hydroponics: Step-By-Step

One of the most crucial steps in a hydroponic garden that is often overlooked is getting the plants in the first place. There is lots of talk on pH levels and nutrients, but these are only suitable for existing gardens.

An up and running system is very different from a germination area, and with the speed that some plants will be growing, you will need to be continually germinating your seeds to keep your garden stocked with new plants to grow.

There are lots of people who skip this step and purchase seedlings that they can drop right into their system. Although this is more convenient, it does mean you might be limited to what you can grow.

When growing from seeds, your plants will bypass any trauma, damage or passing on disease like they would as if they were raised in soil, or other mediums and then transplanted from an outdoor environment into your system.

One other aspect many growers forget is, they can get many more seeds for the price it costs for seedlings.

Although germination of seeds and seedlings can be pretty straightforward, and nature will do some of the hard work for you, there are some bits of equipment you need, terms you need to know, and some specific steps you need to follow to get the best germination rates.

When first starting to germinate from your own seeds, it will be a little more expensive because of the equipment you need to purchase, however, once you are on your way, this cost will be easily absorbed by the number of plants you can grow from seeds.

Hydroponic Germination Basics

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One thing to note right at the start is, seeds can be germinated in soil, but it is advised against doing so. This is for a couple of reasons.

Bacteria can be passed over from the soil to your hydroponic system, and second, it can damage your seedlings roots because they will need washing before they are transplanted. It is far better to use a dedicated growing medium for this such as Rockwool or Coco coir/ Coco peat.

One other thing which is worth mentioning is, there are a lot of places that classify seeds as Hydroponic Seeds, there is no reason to search for this because any seeds are suitable for use in a hydroponic system.

Steps of Seed Germination

When seeds begin to germinate, they start in a dormant state, and then as they grow, they reach an active growing state.

There are 5 parts in this phase and can be seen here:

  • Seed coat – this is the hard outer shell of the seed
  • Plumule – these are the first shoots or stems of an embryo plant
  • Hypocotyl – this is the part beneath the stalks of the seed leaves which sits directly above the root system
  • Radicle – this develops into the first root
  • Cotyledon – these are the embryonic leaves which develop in seed-bearing plants. There will be one or more of these first leaves that you will see from germinating seeds. These help retain nutrients until more dominant leaves start to grow.

When the dormant state comes to an end, the Radicle will crack, and from this, there will be an early shoot. For this to happen, the seeds need to be in warm moist conditions. It is the function of the Cotyledon to provide the seeds with its first nutrients, this they would traditionally get from the soil, but in hydroponic systems, there is no chance for them to do this.

Propagation is the name given to the phase where seedlings start to become stronger, and when they develop stronger roots and their first real leaves. This phase of growth begins as plants emerge from the seed, and ends as they develop roots that have taken hold inside the germination plug.

When plants have developed two or three sets of real leaves, this is the stage when they can be transplanted into the system.

Equipment Needed For Hydroponic Seed Germination

Although there are a few types of growing medium you can use for germinating seeds, it is worth running through them so you can see how they work in your hydroponic garden.

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Coco Peat

This growing medium is a byproduct of the coco growing industry. It comes from the coir fibers and is washed and heat treated before it is made into coco peat products. Most often you find this in the form of large bricks.

The properties that are unique with this medium are, it is sterile, and has natural rooting hormones. It also possesses antifungal properties while being 100% organic. Coco peat can be used anywhere where you would previously use peat moss. Other properties are that it is capable of holding 8-9 times its own weight in water.

Coco peat can store and release nutrients for extended periods to plants, and it delivers fantastic oxygenation properties. Natural pH levels of coco peat are 5.0 – 6.8, so it is bordering neutral and slightly acidic. The one downside of using Coco Peat is some of the loose particles can be washed around your system. This can lead to pump blockages and reservoir sludge.

Coco Coir

This growing medium comes from the same processes as coco peat, but it isn’t ground into fine powder. It differs because it is the hairs that are found on coconut husks. It is most often used in passive hydroponic systems, but it can also come in the form of starter cubes or larger cubes for use later in your system.

Coco coir comes with all of the same properties as coco peat and is an excellent growing medium all around, but it can suffer from the same downside. Coco coir is not clean, and sediment can be washed off leading to the same pump clogs and reservoir sludge buildup. It can be rinsed before use to remove any of these loose particles.


This growing medium isn’t natural and is made by the heating and spinning of specific silica-based materials into thin threads. This is the same process that roof insulation is made with, and should be treated with the same precautions during use.

Rockwool delivers an ideal material which when used, has an almost perfect oxygen to water ratio while being pH neutral. Most often it comes in the form of cubes or plugs at around 1-inch square that are ideal for starting your seeds.

Once these are on their way with germinating, they are easily transplanted into larger cubes that have a hole precut to accommodate the plug. The smaller plugs are also ideal for transplanting into other growing mediums and are suitable for NFT, drip, and deep water culture systems.

Rockwool grow cubes have a pH of around 7.8 which is a little on the alkaline side.

These three mediums can be interchangeable, but for the remainder of this article, we will use Rockwool as the point of reference.

It needs noting, that because Rockwool is like insulation materials, it can make you itch, or breathing the fibers can be harmful. You only need to handle this material as much as required without any unnecessary touching. 

Other items needed

  • Containers that are capable of holding water, Germination tray with dome
  • Chemicals for raising or lowering pH levels
  • Seeds of choice
  • Grow lights if germinating indoors
  • Heating pad if temperatures are lower than required

Germinating Seeds Using Rockwool

Step 1: Hydrating and Stabilizing

Depending on the number of seeds you are looking to germinate, you might need one or more containers. These need to be big enough to hold your Rockwool cubes once they have been soaked in water.

If water levels are too high, the seeds can drown because of the excess water. The seed needs to be at a height where the water can wick up the cube to the seed, but also, there is air available for the seed from above.

At this early stage, you can use distilled water or regular faucet water. Both will work equally as well as each other. Once you have the water in your container, you need to test the pH levels. There are a few growers who recommend adding a half strength or lower nutrient solution, but at this stage, it isn’t necessary, and the seeds won’t benefit that much, and in some cases, once nutrients are added to sprouting seeds, they have died.

Using either a pH test kit or a pH testing meter take a reading. Depending on the type of water you use, it might read up or down, but you might find the water gives a reading of 7.4. This means you will need to lower the pH by using your pH down solution.

The pH you need to aim for is as close to 5.5 – 6 as you can get. At no point should you let the pH drop to below 5.5. The fibers of the Rockwool can become damaged when this happens.

Insert your starter cubes and let them soak for around an hour. By this time, they will have swollen by soaking up the water from the container.

Rockwool cubes have the ability to hold the perfect balance of air to water ratio. If there is unnecessary squeezing, this will change this ratio and can cause deformation of the cube. The cubes are capable of remaining wet for a few days without any additional watering.

If you are presoaking your cubes in pH balanced water before moving them to another tray. Don’t discard the water, and keep it in a sealed bucket for later.

Step 2: Planting Seeds into the Cubes

Depending on the supplier of your Rockwool cubes, you might have the ones which come without holes already in the cubes. If this is the case, all you need to do is make a hole in the top which is to a depth of no more than a quarter of an inch deep.

Now, all you have to do is take a couple of seeds and carefully place them into the hole. They won’t fall to the bottom so you will need a small device to gently push them to the bottom of the hole. Once done, you can gently push another little piece of Rockwool into the hole to cover the seeds. Make sure this is only tight enough to block light from entering.

It might seem backward, but what you do now is cover the container. This will leave the seeds in darkness, but it will also retain moisture and prevent evaporation. It is this environment which is critical for seeds to germinate correctly.

You can purchase dedicated germination trays that come with plastic domes, this isn’t necessary. Other growers also slide their trays inside a Ziploc bag to retain moisture, this though does mean your trays will be much smaller. All you need is an upturned tray of the same size or something that can sit across the tray without pushing on the Rockwool cubes.

No matter what you use to cover your tray, be it a Ziploc, or a plastic dome, your trays need to sit in darkness throughout the germination period. The area where you have your seed trays laying should be around 68F, if your growing/ nursery area is less than this, then this is where the heating pad comes into use. A few degrees above will be fine, but it is below which really causes the problems.

Step 3: Let Nature Take its Course

While the seeds are germinating in this phase, you do need to check water levels on a daily basis depending on how warm your environment. This is one of the advantages of using Rockwool because you might find they don’t require any, or minimal watering during this time.

This is where you can use the reserved water from the first step, simply add enough to keep the blocks moist as water levels drop.

This is also why it is advisable not to add any nutrients at this stage. Sprouts are becoming stronger, and only really need nutrients once they are in your system.

As you added more than one seed to each hole (there will be mortality rates or slow growers), you might find that both have sprouted. It will be tempting to try and remove the one and replant, but you should avoid doing this. It can cause damage to the other sprouts rooting system.

This stage is usually reached in around 3 – 4 days depending on the growing conditions. When you see the first true leaves emerging, it is time to select the smaller of the two shoots and cut off the more minor one’s level with the top of the cube. It is a sacrifice you need to make, unfortunately.

Once plants have reached this stage, it is time for them to start receiving light to help them grow. Many people use sun-facing windows to deliver this light, and although ideal for the first introduction to light, it can cause problems later.

If you use the sun or grow lights, it is the red-light frequency that will accelerate seedlings growth. When using the sun, three hours per day is enough, and the times that contain most of the red light is between 6.00 am, and 9.00 am or later in the early evening from around 4.00pm until 6.00 pm.

Using the window method will require the trays to be turned so the seedlings won’t lean toward the light. Additionally, once your seedlings are getting bigger, they will need up to 15 hours of light per day.

This is where a sun-facing window leads to problems, there might not be enough sun. When this happens, and seedlings don’t receive enough light, they grow weakly and leggy. Once this happens, they begin falling over, and in many cases, it is something they are unable to recover from.

Overhead grow lights solve this problem because you can set the timer for 15 hours per day, and because the lights are overhead, the seedlings won’t lean to the side. Additionally, as they are receiving a full quota of light, they will grow much stronger and healthier.

One other thing to note is that seedlings need time to rest from light, so when they have had their quota, the nursery area should have sufficient darkness.

One final caution is to make sure any grow lights are positioned far enough away from the top of the seedlings so as to not scorch them (depending on light type). As they grow, the lights will need raising. Watering might become more frequent as the seedlings begin taking on more fluids, and if there is heat from your lighting fixtures.

Step 4: Transplanting

The first steps of germination to when you can transplant into your system can take between 2-3 weeks.

Rather than waiting for this time limit, you can check the bottoms of your Rockwool cubes, and when you see the roots are starting to protrude from the bottom, then you can transplant. This can be a good indication because if you leave them too long, they can begin to get root bound in the cube as this will be their only source of moisture.

Once you have reached this stage, you can clear a space in your system for your new young plants. You can transfer the whole plant along with the Rockwool cube into your growing media where you should cover the top lightly.

Because the plants rooting system has been focused on the cube for moisture, it needs a chance to naturally seek out another water source, so, to enable them to do this, you can top water them for the first few days.

Why Haven’t all My Seedlings Survived?

There are numerous reasons why not all seedlings will survive, and not all can be explained. But, depending on plants being grown, there are temperature differences that must be accounted for. if you have cool weather plants, and warm weather plants as seedlings in the same environment, then this could be too much of a temperature swing for either type of plant.

Other things you need to be wary of are as follows:

  • Media drying out – seeds need to be in a warm moist environment to germinate. If they dry in between watering, this can kill them or prevent them from sprouting.
  • Retain high humidity – this is essential to retain moisture. Humidity domes or an upturned tray on top of your grow tray can help maintain moisture and humidity. A transparent dome while under lights will also be beneficial.
  • Too wet – if you over water, or your Rockwool cubes become too wet, this can lead to seeds rotting before they have a chance to germinate properly. To make sure you don’t over water, you can spray inside your grow tray rather than pouring water. Many grow trays have ridged bottoms so the grow cubes won’t be standing in pooled water. If a too wet situation happens, you can have what is called damping off. Here, some molds and fungi form during the propagation phase and cause your seedlings to lose the structure of their stems and lay flat.
  • Don’t overfeed – when you start feeding with nutrients, this should only be when you see the first sets of true leaves. The EC of your water should be at a maximum of 0.8 – 1.2. During the early stages of life, plants will obtain all their nutrients from the cotyledons, and it is only when these first true leaves show they become dependent on external sources of nutrients or fertilizers.

Transplanting Tips

This might appear a simple exercise, but at this stage, plants will be susceptible to transplant shock. This isn’t only from the pressures of being removed from the grow tray, but also from being placed into a new environment. This initial shock can take them a few hours to recover from.

Seedlings are heat sensitive, and even more so when being transplanted. This will include their new life under stronger lighting, but also the temperature of your nutrient mix.

The ideal time to transplant is when your seedlings are ready to be watered. The grow cubes will be slightly moist and will have shrunk back a little in your grow tray. This will make them easier to remove, and when they should be placed into a system that has running water.

Seed Tips

Although there are lots of seeds that are suitable for germination, some more exotic plant seeds do have special requirements. Here is a brief overview of what you might find when looking for seeds.

Pre-soak seeds – some growers advise to presoak seeds before germination. This would allow the seed coat to become saturated and break open easier. However, because hydroponic germination methods are in the mid 90%’s compared to soil, this is not recommended unless the speeds specifically require soaking.

Scarification – many fruit plant seeds might require their exterior to be weakened before germination. In nature, this is the function of animals or birds. To mimic this in hydroponics, this type of seed will require some form of scarification. This might include the seeds being run along a metal file, rubbed across sandpaper, cracked lightly with a hammer or even cut with a knife. If you have any seeds of this nature, be sure to only carry out this process on the seeds you will be using. Once they have been scarified, they will not store very well.

Seed inhibitors – because some seeds expect to lay dormant over the winter period, they have built-in inhibitors that prevent them from germinating too soon. Some of the inhibitors can be found in the way of Abscisic acid. This would decrease in the seeds as winter comes to an end, so the seeds are ready to sprout. To overcome this, you can place this type of seed in a moist growing medium and placed in a refrigerator for four weeks. This process is called stratification, and it is by doing this that enzymes break down and mimic what happens in the wild. Temperate native plants that require this winter season will need this process. It might be uncommon, but it is useful knowing how you can work around it.

One other inhibitor which can be found in desert plants is phenolic compounds. This prevents the seeds from germinating until there is sufficient moisture, This inhibitor is water soluble, and once it has been broken down, then the seed is able to sprout. All it requires for these to sprout is sufficient moisture.

Temperature – We have spoken about temperature, but it is worth mentioning the upper heat limits because this can prevent seeds from germinating, or even killing them. If the growing media rises above 90F, then you will unlikely see any action. You can check this with a hydroponic thermometer quite easily. In many cases, this happens in greenhouses where growers germinate, but having the ideal temperature is crucial.


There can seem to be a lot of information to take in when it comes to hydroponic seed germination, but in practice, it is quite straightforward when you follow the requirements. The amount of equipment is minimal, and the only things are to make sure you have an area that you can use as a nursery.

In many cases, it can be something as simple as a shelf racking system where you can store your trays and is away from your system grow lights. If you use this, you can easily keep your seeds covered until they are ready to be introduced to grow lights, and the amount of shock they will face during transplanting can be reduced.

With the length of time required before transplanting, you can have seedlings at various stages and always have a continual supply of plants that you can add to your system. This makes the system more efficient overall.

Growers also find that growing their own plants from seeds, is not only cost effective, but it is also gratifying to complete every single stage of their plant’s growth.

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How to Test EC in Water – Complete Guide to Electrical Conductivity

Hydroponic growers are faced with many challenges when it comes to monitoring their nutrient solutions and pH levels. We know this can affect how plants grow because some plants require very different ratios to grow to their full potential.

If these two factors were challenging enough, there is one more element in nutrient solutions that needs constant monitoring and adjusting when required. This is the EC level, and here we will see how it affects your plants, how you can test it and how you can adjust it if needed.

Understanding EC Levels

What is the EC in a Nutrient Mix?

EC is the measure of electrical conductivity in any solution. You might also see it as CF which stands for the ‘Conductivity Factor.’

On many occasions, you will see this EC written in conjunction with nutrient solutions pH levels. At this point, you need to know the difference between the two.

The pH levels of your nutrient mix give an indication of nutrient balance in your mix. EC, on the other hand, is an excellent guide to the quantity of available nutrients in your solution.

To make this easy to understand, distilled water contains no EC because it has no minerals contained in it. Once there is an introduction of minerals, salts are dissolved, and then the solution can conduct electricity. The higher the amount of salts, the higher the EC level or the electrical conductivity.

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One thing worth noting with EC levels is, it doesn’t tell you what nutrients, and at what levels they are at, it is an overall number of nutrient concentration.

EC Levels in Hydroponics and Why They are Important

Just like pH levels in your hydroponic system, and some plants prefer different levels. It is the same with EC levels, and various plants prefer different levels. On top of this, most plants like the EC level to be in the range of 1.2 – 1.6 in their vegetative stage, and once they reach flowering, they like the EC to be in the range of 1.6 to 2.4.

These levels are worth knowing because, from the following three plants, you can see a vast difference between what levels they prefer.

  • Basil & other herbs – EC 0.8 – 1.4
  • Tomatoes – EC 2.2 – 2.8
  • Spinach – EC up to 3.5

Now we know what can affect EC levels, we need to understand why they are essential. These levels provide a detailed indication of what is happening in your nutrient solution, especially when tests are carried out as an addition to testing pH levels alone.

Here is a brief overview of what is happening with plants when the EC levels change:

  • EC level remains the same – the plants are absorbing the same amount of water as nutrients. When this happens, and reservoir levels drop, you need to top up with a nutrient mix of the same strength. This does still require checking once it has stabilized and run through your system.
  • EC levels drop – when this happens, it shows the plants are using more nutrients (salts) than they are using water. When this happens, you need to top back up your reservoir to the level it was, and it might mean you need to make the concentration of your newly added nutrients a little stronger. This does need to be checked after topping up in case your solution ends up too strong.
  • EC levels rise – this happens when your plants are using more water than they are using nutrients. You may have seen this and know the symptoms as ‘Nutrient burn.’ To resolve this, you need to dilute the solution with more water. Again, your solution will require checking in case it falls off and goes in the opposite direction.

EC Levels and Plant Growth

There are a few things growers should know about EC levels, and this is what happens to a plants growth, and what factors can make EC levels change. There are elements which can affect these levels aside from the amount of nutrients plants are absorbing.

We have seen why these levels are significant, and here is how it affects plants during different stages of their growth.

How Conductivity Levels Will Affect Plant Growth

Seedlings, cuttings or delicate plants will suffer from nutrient burn when the EC level is too high. This ‘too high’ doesn’t mean you have it wrong because even a nutrient mix that is suitable for larger plants can be too strong. To make sure your plants don’t suffer from nutrient burn during these stages, it is advisable to run your nutrient levels at half strength or lower.

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Once plants become more substantial and are entering their vegetative stage, you can increase the nutrient concentration. This is still dependent on the type of plant you are growing. If you have a mixture of plants, you need to separate these into light feeders, medium feeders, and heavy feeders if possible. If you have three different types of plants which all feed at different rates, this means you will need three separate reservoirs.

This might seem too much, and it might not fit in with everyone’s hydroponic system, but as a good example. If you feed lettuce with high EC levels that are suited to tomatoes, then your lettuce will become bitter. At the other end of the scale, if you feed tomatoes with low EC levels intended for lettuce, then your tomatoes won’t have any taste.

Can Water Temperature Affect EC Levels?

Nutrient solutions in your reservoir should fall inside the temperature range of 65 – 80 degrees Fahrenheit. Plants don’t like a rapid change in water temperature. This is more important around the root zone. When you are about to add water to your reservoir, you should make sure it is at the same temperature as what is already in the reservoir.

If your grow room is indoors and you fill from an outside hose, this could cause too much of a difference.

Ambient temperatures will also have an effect, so depending on where your system is situated, you might need to make use of an aquarium heater for colder regions, or a suitable chiller for your nutrient solution if you live in warmer climates.

How Does Air Affect EC Levels?

All growers know that plants require airflow to grow correctly, but many are not aware that ventilation plays a significant part in EC levels.

One thing to note is that airflow isn’t the same as ventilation. Airflow is the moving of the same air while ventilation is discarding of old air while introducing fresh air. When you have improved ventilation in your growing area, this aids much higher rates of transpiration. From this, plants will increase their rate of nutrient absorption and uptake.

EC Management

When you have a good EC management procedure in place, you are in a position to help your plants deal with changing conditions. Many growers use low-light conditions and raise their EC levels. This restricts vegetative growth and helps counteract stretching.

When plants are in low humidity areas with high heat, growers can reduce their EC levels to ease any stress on their plants.

Testing EC Levels in Hydroponics

Testing EC levels is no harder than testing pH levels in your solution, but there are a few terms and things you should know.

Terminology Related to EC Levels

  • EC Electrical Conductivity. A measure of the total dissolved salts/ solids in your nutrient solution.
  • CF – Conductivity Factor. Another term for the above EC.
  • TDS – Total Dissolved Solids. This is read in ppm (Parts Per Million)
  • PPM – Parts Per Million. This is a standard measuring unit of elements which are in your nutrient solution. When you have one ppm, this equates to one part of the (solid) weight of any given mineral in one million parts of the solution.
  • MilliSiemens – this is a measure of electrical conductance

Converting Between TDS and EC Values

Again, this might sound complicated, and when you come to take readings, your testing meter will do this conversion for you for whichever value you are using.

When you want to find the approximate values of sodium chloride (salt) TDS in your solution, all you need to do is to multiply your EC reading (in milliSiemens/cm) by 1000, and then divide the result by 2.

If you want to convert the other way to find out an EC level from a TDS reading, it is a matter of doing things in reverse. All you need to do here is multiply your ppm reading by two, and then divide the result by 1000.

It is far better to rely on a meter when it comes to taking readings than converting manually.

The EC vs. TDS Debate

There has been a debate in the hydroponics world, and this is because you can test nutrient solutions with different TDS meters and come up with mixed results. This purely boils down to there being different conversion factors, and some manufacturers use different calculations to come up their results. No matter which meter you use for TDS readings, you should only take the results as what they are, an approximation.

These TDS meters use an internal conversion formula to display the EC level as an average ppm. In most cases, this comes out at a 700:1 ratio. This will mean that when you have an EC of 1, you then have 700 ppm. Other makers of these meters use 500:1 ratios for their calculations, and with this difference, it is easy to see why there is such a debate.

The safest route for growers is in using the 700:1 ratio and the reason for this being it is safer and better for your plants to add too little nutrients. If they begin showing signs of nutrient deficiency, then it is much easier to add more than to dial back the strength to a weaker solution.

To reiterate about nutrient strength during different stages of plant growth, you are far better to keep things simple and using nutrient solutions at half-strength during any vegetative phase, and then increasing them to full strength during flowering and fruiting stages.

To keep things on a level, it should also be standard practice to empty and refill your reservoir on a regular basis

The good news is, when you read EC levels, this will return the same results no matter who manufactures the meter.

EC Meters

Testing meters come with many names. They can be EC meters, CF meters, and Truncheon meters. These are all basically the same device, but in looks, they might appear very different.

Digital EC meters can take readings and do all the calculations for you internally. A Truncheon meter, on the other hand, does a reading, and on the side, there are 3 scales, so when the mark stops, you then have your three levels.

For new growers, these digital meters are the better option. They can be faster in operation, and although the Truncheon meter is manually read, it is a lot more expensive than digital.

When taking EC readings, this needs to be performed on a daily basis because things can change rapidly, and as we saw earlier, weather and ambient temperatures can play a large part in these changes.

Here are some simple use and maintenance steps for using a digital EC meter.

Maintenance of an EC Meter

  1. Always be sure to stick to the manufacturer’s instructions and recommendations
  2. Once you have used the device, always clean the electrode with distilled water and carefully dry with a lint-free cloth.
  3. On a regular basis, you should clean the electrode with rubbing alcohol. To do this dip and swirl around before giving it a good rinse with distilled water, and drying is as above.
  4. If there is any reason you need to store it for extended periods, always remove the batteries.

Using an EC Meter to Take Readings

  1. Remove the end cap which protects the electrode.
  2. Dip the probe into your reservoir and hold in place for up to 2 minutes or as advised by the maker of the meter. During this time, the meter will be reaching the same temperature as your nutrient solution.
  3. Once done, you can pull out the device and take the reading from the digital display. Many meters come with various buttons you can press to reach the other readings.

Organic Fertilizers and EC Levels

While reading EC levels can be very beneficial for your hydroponics system, when growers use organic fertilizers things can become very misleading. This is because the molecules in organic fertilizers usually don’t conduct any electricity.

Growers are still recommended to take EC readings with the aim of determining the soluble salt levels.

It is the case though that many of the nutrients won’t register on EC readings due to the form they are in. In most cases, they won’t have been broken down into simple salts. When readings are taken with EC meters, the gained results will more than likely read much lower than if they were using non-organic nutrients.

What growers tend to find is that although readings are lower, plants are showing no signs of deficiency. This means that nutrient profiles must be adjusted for use with these organic fertilizers.

Calcium can be one mineral which is lacking and can sit at around 100 ppm which is a long way from the recommended 200 ppm for leafy green vegetables. But, with the level at only half of the suggested, these leafy greens don’t show signs of calcium deficiency. One compound that can be added to rectify this is calcium sulfate.

It has been found both calcium and magnesium lacking when using organic fertilizers, but, if growers are using regular water, these deficiencies can be made up. However, this doesn’t help if you are using pure water.

Regular water contains 30 ppm of both calcium and magnesium, and over extended periods (several months) calcium levels naturally increase inside your reservoir, and can almost reach the recommended 200 ppm. Magnesium can naturally increase over time in the same way.

One thing which has been found when using organic fertilizers is that the smaller the reservoir, the more frequent testing must be carried out.


As you can see, on paper EC levels, look hard to control, but in reality, they are as easy to test for and to adjust as pH levels are.

Learning how to fine tune your hydroponic EC levels brings many more benefits than choosing to ignore it, and this can be evident when you have symptoms such as nutrient burn, or you are beginning to have vegetables with little taste.

All the formula are best remembered, but with a digital meter to take the readings, adjusting your EC levels works out to nothing more than dilution. As long as you can keep the EC levels on the right side, it is straightforward to adjust so your plants can grow to their full potential.

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How to Test The pH Of Water (Complete Guide)

When hydroponic growers first begin running their systems, there is one aspect that is so very often overlooked. This is the importance of the pH level of the water and nutrient solution. If this isn’t around the ideal levels, it can have a dramatic impact on your plants. The most significant thing with a solution pH is it can go up as well as down rather than only in one direction.

If this wasn’t enough, some plants require different levels, so setting the pH to one level can cause harm so some plants if they’re fed from the same reservoir.

Here, we will take a look at all you need to know about the pH of water, how you can adequately test it, track it, and control it for the benefit of your plants.

Understanding a Hydroponics Systems pH Levels

An Introduction to pH

What is it, and why is it so crucial in hydroponics? The meaning for the term pH means Potential Hydrogen, and it is one of the most essential parts leading to healthy plant growth.

All types of water have a different pH level. Tap water to bottled water and water in your system will all vary. When we measure this, there is a scale which reads from 0 – 14, and zero being the most acidic while at the other end of the range, 14 is the most alkaline.

Neutral levels are found at number 7, and this like our body is the region which plants thrive best. With this being said, there are a few plants which prefer a pH level slightly outside the range we consider neutral.

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When we look at what this means for our systems, the ideal or standard pH for plants to thrive is under a neutral level, roughly around 5.5 and 6.5. But, there are a few plants that like the other side of the scale and grow best in the region of 8.

When the pH level is correct, it allows plants to absorb all of the essential micro, and macronutrients they need through their root system. Additionally, it is in this ideal range when there are higher uptake levels of the all-important NPK (Nitrogen, Phosphorus, and Potassium) which maximizes plants growing ability.

Understanding the pH Levels of the Plants You are Growing

Plants which are grown in the soil, grow equally well in soils that have varying pH levels and will range from around 6 (slightly acidic) to 7 (neutral). In a hydroponic system in most cases, plants need pH levels which are a little under the recommended for soil.

Here is a list of ideal hydroponic pH levels for a range of plants:

PlantIdeal pH range
Asparagus6.0- 8.0
Broad Bean6.0-6.5
Brussel Sprouts6.5
Chili peppers5.5-6.5

This list is by no means extensive and these are indicative of the levels required.

Testing and Measuring the pH of your Hydroponic Nutrient Solution

If you are a new grower, you will need a daily check of your solution to check the pH levels. After a while, you will come to understand your system and how all of the nutrient concentrations and water type you are using will affect the levels.

Before heading off with testing methods, it is essential to know the effect that different water types can have on a hydroponic system, and why many growers decide to use reverse osmosis water rather than tap water.

EC levels are the amount of conductivity the nutrient solution can have, or in simple terms, the amount of electricity that can pass through the solution. EC is dictated by the salt levels that are in a solution. EC though doesn’t tell you what salts are in your mix, and hence the reason for growers using reverse osmosis water. They want a clean slate where to begin so there is no guessing.

Once they have this water, they can take their nutrient bottles, and will then know precisely what will be in their solution. A point to note here is, never purchase nutrients that don’t come with a guaranteed analysis, or they are from a highly reputable company. All too often cheap nutrients can cause more harm than good to your plants.

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By using good water, the levels of pH will require less adjusting, and by doing so will give less shock to your plants. Now, you can either decide to use reverse osmosis water from the beginning, or you can adjust the EC levels and then focus on your pH levels.

Ways of Measuring pH Levels in Hydroponic Systems

There are three ways in which you can measure your pH levels in your system. Here is an overview of methods available.

Litmus Test Strips

The simplest way is by means of litmus paper strips. Litmus paper contains a dye which is sensitive to the liquid it is dipped into.

In this case, it would be a sample of your nutrient solution. Once you have this sample and you have dipped your strip, you wait until the color changes, and this is then compared to a chart which shows the pH level.

Although this method is the cheapest, it isn’t the most reliable. Some of the colors for the different levels are very close, and comparing a small squab can leave you guessing at which one it is. For some plants, this approximate measure of the difference in pH might not be significant, but for others it can leave your plant battling for survival!

For a quick means of testing, they are handy to keep close to your growing area, but shouldn’t be relied on.

Liquid pH Testing Kits for Hydroponics

This liquid pH testing kits cost slightly more than their litmus counterparts, but with this price increase, there is more accuracy. This form of testing is commonly found for people who have swimming pools, so the process has been well tested over the years.

The way you perform this test is to take a sample of your nutrient mix, and then place a few drops of sensitive dye into the container. After a short while, the color changes and is then compared to a chart representing the pH levels similar to the first method.

Like the first option, there are drawbacks and the most significant being the color shades can be hard to detect and interpret. Both these tests should be carried out in good lighting conditions so as not to affect reading the colors.

Testing Hydroponic pH Levels with an Electric Meter

The final option is the most expensive, but it does give exact results without growers misinterpreting the reading of a color chart. These electronic pH testing meters vary in design, size, and price. One of the most common varieties is a digital pH pen. Once this is placed in the sample of the nutrient mix, it will give a digital reading of the exact level.

Although these are precise in their readings, this can vary over time, and they do need calibrating on a regular basis. In some cases, this can be weekly. This might seem to be a little overkill for some growers, but when it can be the difference between healthy plants, and ones which are suffering from a nutrient lockout, it can be a chore worth doing.

What you Need for Calibrating a pH Pen

There are two forms of calibration for these pens. One is digital, and the second being ones which can be manually calibrated. We will run through calibration of both, and first off is the equipment you will need:

  • Your pH Pen
  • Calibration solutions: One at pH 4, pH 7 and pH 10
  • Distilled water
  • Small measuring cups
  • Gloves
  • A small screwdriver will be required if you have a manually calibrated pH Pen

Digital pH Pen Calibration

Many of the pens use similar methods for calibration, so these steps will more than likely suffice for whatever digital pen you have.

  1. While wearing gloves, pour a small amount of the calibration liquid into separate measuring cups (solution must be room temperature). Now you will have one for 4, 7 and the third for pH 10. This solution should be as fresh as possible, so when purchasing, refrain from thinking a large bottle is leading to a cost saving.
  2. Before commencing, ensure the pens probe is clean, (Refer to cleaning pH pen section).
  3. Check the pens instructions for performing the test on the pH 4 solution. Most pens have a guide marker where you should submerge the pen too, when it as at this level, gently swirl it in the solution.
  4. Rinse the probe with distilled water, and then test on the two higher pH solutions.
  5. Not all pens require a 3-step test, but the more calibration points, the more accurate your pen will be.

Calibrating a Manual pH Pen

Although it might sound harder to calibrate your pH device by using a screwdriver, the process is straightforward. The actual testing phase is exactly the same, and all you do with the screwdriver is adjust the dial to match up with the pH.

Again, the more often you perform this calibration, the more accurate the results you will obtain. For anyone with an average sized garden, a period of between 2 to 3 feeds should be okay for pen calibration.

Cleaning of a pH Pen

Before use and in between calibration tests, the probe on the device needs to be clean. For 15 minutes before you conduct your solution testing, the electrode needs to be soaked in a buffering solution. If you have none of this solution, refrain from using any other water, because even distilled can erode the glass membrane.

If your pens electrode has been allowed to dry, you must soak it in the storage solution or a cup of pH 7 buffer solution before performing your testing. If the pen has been in storage, gently shake it up and down to disperse any bubbles which may have formed.

Keeping the electrode clean is one way not to affect the operation of the device. You should never wipe the electrode because this can affect any static charge in the device. Gently blot the device and bulb with lint-free paper. You should also be sure to never touch the bulb with your fingers, if you don’t damage the device probe, you can leave behind a residue that will stop the device from giving accurate results.

Some devices need storing in a recommended storage solution. These can be purchased, and when the device is stored and cleaned as instructed, they will deliver fast and accurate results.

pH Levels of Different Hydroponic Systems

Now we have seen the equipment you can use to test your solution, and how you need to calibrate your device. We will take a look at how different systems can have different pH levels. NFT is straightforward because the solution is in direct contact with the roots.

If you have a media based system, the readings can be a little more intense. Two readings need to be taken, one from your reservoir, and the second from the runoff solution (the leachate). If you have large plants, then there will be a difference in this before and after scenario. When you come to adjust your solution, you need to base the adjustments to your reservoir based on the pH of the leachate solution. This adjustment is required because it will be the level of PH your plants will be experiencing rather than the pH which is in the reservoir.

Adjusting Hydroponic pH Levels

There are a few reasons why your pH levels will rise or fall, and luckily, it can be quite easy to fix them. One of the easiest ways to avoid any spikes or drops in levels is to make sure your nutrient solutions contain pH buffers.

Many of the nutrient suppliers will also offer solutions which can raise or lower pH levels as required. One of the most well-used is pH UP and pH Down from General Hydroponics. When using these, it is crucial to follow the recommended doses, and in relation to how close to the desired levels your solution is when you test.

If your pH levels swing too far in either direction, plants can suffer from the nutrient lockout, so it is vital to regularly test these levels until you have a better understanding. When it comes to making these adjustments, there are only a few steps involved:

  1. Depending on your reading – add 1-2 ml of pH Up or pH Down per gallon of water.
  2. Stir your solution and wait for 30-minutes before testing your solution a second time
  3. Repeat as necessary until you reach the desired range for your plants

Your pH levels will change when you add nutrients, so you should always test once these have been added to a fresh tank. Apart from that, it is advisable to check around the same time on each day. There are a couple of natural methods to adjust pH if you are out of any pH Up or pH Down. These are a short term fix and should only be used if it is absolutely necessary.

Citric acid or white vinegar can be used to lower pH, while baking soda can be used to raise your pH levels.

Maintaining pH Levels in Hydroponic Systems

To finish off, here is a quick recap of how you can maintain your pH levels:

  • Check levels on a daily basis until you understand your system. After this, and you gain experience, once or twice per week might be enough.
  • Use the best testing kit you can. Litmus strips are best used for quick periodic testing.
  • If you see your pH levels are between 5.8 – 6.5, don’t be tempted to adjust anything. This is ideal for the majority of plants.
  • If your solution is too high then lower it with pH Down (phosphoric acid).
  • If the level is too low, then raise it with pH UP (potassium hydroxide).
  • Don’t rush for a quick fix to your pH levels, too much too quickly will shock your plants.
  • Keep records of how much solution you add to your tank.

Depending on where you live and are using tap water, you might not require too much adjustment, but for hard water areas, the change can be more significant.

Overdosing with either of these pH adjusters or nutrients can be harmful to your plants. Additionally, if your solution levels drop in your tank, then the pH levels will be changing at the same time. Much can be said if you are topping your tank with water, again your levels will vary.

Understanding pH levels is one of the best skills any hydroponic grower should take the time to learn.

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How to Prevent and Treat Root Rot in Hydroponics

Many problems face hydroponic growers at different stages, and one of the most common can go undetected for a while and can cause severe amounts of damage to plants.

Root rot is a disease that can affect every single grower, and the symptoms can lead us all to think it is a deficiency in another area. Plants can begin wilting or showing signs of nutrient burn, or they might die altogether. There are many reasons these symptoms can happen from lighting, pests nutrients or feeding cycles, but in the end, it is a case of root rot.

Once we gain some experience, and if our plants have suffered from root rot, it’s a thing we always know to look out for. But, if we are unaware of what to look for, there is no way we’ll know how to prevent it, and how we can treat root rot in our hydroponic systems.

What Causes Root Rot in Hydroponics?

Root rot can affect plants in different ways. This will depend on if they are a flowering type, or they are crops such as lettuce or herbs. You will see plants can have symptoms such as curling leaves in an upward or downward direction, plants have slow growth, or there is yellowing in the leaves.

One of the reasons that makes root rot hard to detect can be that, it might be affecting all of your plants at the same time. All plants can suffer from stunted growth at the same time, so it might appear there is another problem.

The primary cause for root rot is insufficient levels of oxygen reaching your plant’s root systems. This is more often found in Deep Water Culture systems or systems where roots are exposed to water for extended periods.

You can quickly see if there is a problem by lifting your tank lid and see if it smells funny, this is a clear sign you have root rot in your system. Next, you can look at your plant’s roots. Some roots can become tinted from the nutrients they are absorbing, but if they appear to be brown and slimy, then this is a clear sign root rot has already set in.

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It might sound like a simple problem to overcome. Monitoring your water levels and making sure there is plenty of air won’t be enough, because at this stage, something else will most likely be occurring.

Mold and pathogens such as Pythium and Phytophthora are water molds which can attack plants when the conditions are right. Nutrient solutions which are too warm produce the ideal conditions for these molds to grow, and they will rapidly infect all your system.

The spores of Pythium and Phytophthora become immobilized and can survive for several months. They take up home in the dying roots and are dispersed via reused growing media, polluted water or a system which has become contaminated. Even other equipment or things you handle can be enough to reintroduce these spores back into a clean system.

Either during this stage, or the first stages of root rot, a coating of slime will form around the roots. This barrier is strong enough to prevent any oxygen from reaching the roots, and it is this that allows these pathogens to worm their way in and smother any part of the root system.

Treating Root Rot in a Hydroponics System

A lot of what you can do to treat root rot will be the same as what you can carry out for prevention. But, there are a couple of things you can do to immediately tackle the problem is there are only a few plants which are infected.

If plant leaves are showing signs of dead matter, all this should be removed and discarded away from your growing room. You can remove your plants and physically clean the root system. If you do this over a sink, you can remove anything that is dead or slimy from the roots.

The next stage is to soak the root bed in a sterilizing agent up to a maximum of 12 hours. One product which is ideal for this is Physan 20. It should be noted, this product doesn’t know the difference between bad bacteria or good bacteria. This can also be an excellent time to begin sterilizing any growing equipment you have.

The addition of root builders can also be beneficial in helping roots grow stronger. These are packed full of good bacteria and help to aerate your nutrient solution. Many growers also use this as an addition to their regular feeding schedule as a way to boost plant growth and claim impressive results.

One other type of compound which can be added are microbial inoculant mixtures, these also help with new growth in the rooting system, and also aid in the eradication of diseases. The bacteria in these lead to the breakdown of what is causing the root rot.

Both the root builders or the microbial inoculants can be added as a prevention rather than a cure. However, these methods should not be relied on as the overall way of preventing root rot, this will come down to many other factors which will need your attention.

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If you are looking for a natural remedy for root rot rather than using any of the above chemicals. The following natural recipe was devised by Heisenberg, who is a member of the rollitup forum. The following methods help breed beneficial microbes in DWC systems.

The following recipe needs to be added after you have performed the previous root sterilization, and system clean with Physan 20. This formulation isn’t added directly to your nutrient solution but formulated as a tea, which you then add as required. To make this tea, you do need to purchase a few ingredients, some of which are discontinued so we will provide alternatives.

Hydroguard or any solution that contains the bacteria Bacillus genus can be used. Hydroguard has plenty of good reviews, but the Hydroguard solution requires use within six months of opening, so it is better to order the smallest bottle required.

Great White comes from the same company as the root builder specified above, it delivers explosive root growth and contains mycorrhizal fungus that is well suited for a variety of plants.

Ancient Forest consists of 100% pure forest humus and contains a high diversity of microorganisms. This can be replaced by any earthworm casting product, but this is produced by General Hydroponics who are well renowned for superior products.

Before proceeding with the formula, there was an edit to the post. Both the Hydroguard and the Great White solutions can be replaced by Mycogrow soluble as a cheaper alternative.

Heisenberg Natural Formula Steps (Edited)

  1. Add 2 gallons of non-chlorinated water to a clean bucket, and add two air stones. For this to be effective, you need as much air as possible.
  2. Now, add 15-30ml of Hydroguard and about 1/4 to 1/2 scoop of the Great White powder (these are approximate, just don’t go overboard).
  3. Take an old pair of stockings or pantyhose and place 2 handfuls of Ancient Forest (or EWC alternative) inside.
  4. Tie off and place over one of the air stones in the solution. You can also put one air stone inside the stocking to give more stimulation. This method is more straightforward than straining two gallons of tea if you add the Ancient Forest directly to the bucket.
  5. Add one tablespoon of molasses. This wakes the microbes and gives them something to eat. Never add molasses to your nutrient tank. The beneficial bacteria will die in the tank due to starvation, but you will be replacing these, so it is okay.
  6. Let your tea solution bubble for 48-hours at room temperature. You can use it after 24, but it is more effective at 48. If you are using EWC, the water will foam, this is normal.
  7. After 48 hours, you can store your tea in the refrigerator where it can stay fresh for up to 10 days. If it begins to go bad, you can smell a bad odor. If you smell anything like rotting or sweaty socks, throw it away and make a new batch. Your fresh tea can smell of earth or slightly mushroomy.
  8. To start, add 1 cup to your nutrient tank for every gallon of water.
  9. Add 1 cup to the tank at 3-day intervals.
  10. You can drizzle a little of the tea at the base of your plant stalks. This helps inoculate the root crown (plant dependent). The solution can become cloudy, but your roots will remain white and highly stimulated.

When you multiply microbes with this method, your products will last longer. Once you have ridden your roots of slime build-up from root rot, you can add 1 cup for every 10 gallons at one-week intervals to help prevent future outbreaks.

Prevention of Root Rot in Your Hydroponic Systems

As we can see from the above information, root rot is a culmination of different elements and organisms. Before looking at how we can prevent root rot in your systems, here is a quick recap of the factors which can lead to its appearance:

  • Dead or decaying matter in the reservoir – any dead leaves can start something terrible.
  • Lack of oxygen – Once water becomes stationary, it becomes stagnant, and there is no oxygen passing to your roots.
  • Heat – Warm nutrient solutions make it easy for bacteria to reproduce. A cool reservoir makes it harder for bacteria and fungi to survive.
  • Agitating young roots: When roots are young, they need a chance to build up their defenses. Moving them will weaken these and expose them to pathogens that can quickly attack.
  • Light leaking into the reservoir – This can be a boost to any unwanted growths.

Solutions to Prevent Root Rot

To not only get rid of but to also prevent root rot, you need to take a two-pronged approach. This includes:

  1. Directly treating the plant’s roots – same as above in treating against root rot.
  2. Changing your plant’s environment – changing how plants are growing, so root rot is unable to.

Some of the following procedures will be the same as the treatment steps above but are crucial steps nonetheless.

Adding Beneficial Root Bacteria

As prevention, these beneficial bacteria can be added throughout your plant’s growth. Once mixed with the water, they are a handy way of preventing and treating root-related diseases while making sure nutrients are available to your plants. Subculture B, Rooters and Piranha being alternatives to the preferred formula Hydroguard.

The one bacteria that is most beneficial is Bacillus Amyloliquefaciens because it will survive better in reservoirs than other forms of Bacillus bacteria while fighting a vast number of root ailments.

Plenty of Bubbles

Because lack of oxygen in your system is the primary cause of root rot, it is essential to make sure you have plenty of bubbles. If everything appears to be okay in your system, and you are still showing symptoms, it might mean you need a secondary air pump, or a larger unit altogether.

Root rot can’t thrive in an oxygenated environment, but, it is also crucial to make sure your roots are not being overly disturbed. You can never have too much oxygen in your water, so finding the ideal position for your pump will bring nothing but benefits. You can find some air pumps with dual outlets. These can either be placed in separate tanks or different locations to maintain healthy air flow.

One pro tip is to make sure your hoses are black so no light can penetrate.

A Cool Grow Room

It is essential your growing area is under 80F with the ideal being under 75F if possible. This is the easiest way you can lower your reservoir temperature without the use of a chiller unit. The warmer solutions become, the less dissolved oxygen they can retain, and then can’t pass the highest oxygen amounts to your plants.

Using one of the supplements mentioned, you can let you run your system a few degrees warmer, but it is far better to try and maintain around the optimal 72F for your water.

Being Clean and Sterile

Any dead leaves or debris that find their way into your reservoir will become a breeding ground for bacteria. Cleanliness extends way beyond your reservoir and includes all of your growing areas. One bit of advice is to thoroughly clean all of your growing tools either in between growing periods or on a routine basis. Hydrogen peroxide only delivers a temporary solution. Anything stronger and you need to make sure it doesn’t find its way to your system.

When you have a regular cleaning routine, this goes a long way to letting any pathogens survive in your growing area and hydroponic system.

Stop Disturbing Roots

With the way a hydroponic system works, it is essential for you to change your water on a regular basis. When you do this, you can disturb the rooting systems. In the later stages of plant growth (flowering stage), these become sensitive to pH and nutrients. Changing water between one week and ten days helps plants access nutrients easier.

What is crucial is do not disturb plants when they are seedlings or clones and are trying to become established in your system. At this stage, they lack a colony of beneficial bacteria and have not developed their own biofilm which helps protect their roots against pathogens.

If you are in need of changing a full reservoir, this can severely upset the balance, and young roots might find they have to start again from scratch.

During the first few weeks of a plants growth (plant dependent), it is advisable to only top the reservoir up with additional nutrient water before making a full change and system flush. It is, for this reason, it is a continual struggle against root rot.

Prevent Light Entering Your Reservoir

As much as harmful bacteria and organisms love the light, roots hate it in equal amounts (think air pruning). If you are using grow lights, this problem is worsened because you are giving everything these bacteria need to thrive.

DWC reservoirs are kept in almost pitch black by a lot of hydroponic growers. To be sure you have a reservoir which is capable of fending off any light, there are a few things you can do to help.

  • Use black tubing – This stops light leaks which might not be obvious.
  • Reflective coverings – Your reservoir lid could be getting warm from your grow lights if it is dark in color. However, using a reflective material can prevent heat seeping through the cover and warming your reservoir interior.
  • Reservoir construction – there are many reservoirs which have a thin wall construction. The thicker you can get the better because these are less likely to let any light soak through.
  • Taping light leaks – light can get in all sorts of cracks and gaps. Be sure to tape these with thick tape that will prevent light seepage.
  • Net pot light seepage – you can cover the tops of net pots to prevent light soaking through the growing media. Net pot covers are a quick and easy way to avoid this.
  • Black tubing – dark tubes can prevent light exposure to your reservoir. This often goes unnoticed.


There are plenty of hydroponic growers who throw in the towel if they find out they have root rot, and get rid of all their plants and start again. However, not all occasions require anything this drastic, and the same problem can occur if there are no preventative measures in place.

It can be more beneficial to get root rot and save your plants, because this way, you will know the symptoms, and best of all, you will know how to tackle the problems. There will be occasions when you can’t save your plants, but when you know there is something you can do, it will reduce the chances of losing any crops at a later date.

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