One thing growers should never overlook in their hydroponic system is the temperature of their nutrient mixture. As soon as the temperature reaches over a certain point, the solution can’t hold the dissolved oxygen as long.

Add to this, when there are unhealthy root masses mixed with these temperatures, it creates the perfect place for pathogens like root rot to take a foothold. To combat these problems, you need to make sure your nutrient solution remains between 65 and 75 degrees.

Here we will look at ways to cool your hydroponic reservoir and solution. While these can make the difference, some of these methods come with their own downsides when in use.

In summary, according to other sites such as NoSoilSolutions and Epic Gardening, here are the main eight ways to cool a nutrient reservoir.

1. Keeping your reservoir in the shade
2. Paint your reservoir to reflect light
3. Increasing the size of your reservoir
4. Top off your nutrient solution
5. Bury your reservoir in the ground
6. Making a swamp cooler
7. Making your own cooling coil
8. Purchase a water chiller

How Can I Cool My Hydroponic Reservoir?

Here we will take an in-depth look at the above methods. The first couple of entries in the list should ideally be done as a matter of course. Aside from controlling temperatures, they help prevent light entering and the growth of algae.

1# Keep Your Reservoir in the Shade

Any grower should be doing this one thing by default. Being able to minimize the amount of light which falls on your reservoir will help prevent it from warming up in the first place. Aside from this, you also need to be sure no light is entering your reservoir, this will warm it quicker, and it does allow algae to form along the water line.

2# Paint or Insulate Your Reservoir

There are two things you can try in this solution. The problem doesn’t just come from tanks, which are in a warm environment. Nutrient tanks can catch the heat from grow lights. As soon as this starts to hit the dark colors of your tanks, then the solution inside begins to warm up.

Solutions for this are to either paint your reservoir a light color as a way of reflecting the light and the heat, or you can cover your tank in a reflective insulation material. Even regular insulation can be enough to help maintain cooler temperatures in your tank, yet reflective insulation comes with an added benefit.

Once your grow lights hit the top of your tank, this reflective material bounces light back, which can reach the undersides of your plants.

In summary, here are things to know about painting or insulating your tank:

• Don’t choose a light plastic to save on painting, this can lead to algae growth when light passes through
• Dark plastics absorb more heat while light colors reflect
• Reflective insulation helps cool, and throws light back onto your plants

3# Increase Your Reservoir Size

Depending where hydroponic gardens are located, this often dictates the size of reservoir in use. For small gardens, growers tend to go for a smaller tank to match, however, these warm up quicker than larger reservoirs.

If you add a larger reservoir, your nutrient mix becomes more stable. This doesn’t just mean you can keep lower temperatures, but also it helps balance pH levels, PPM and other concentrations in your mixture.

• Small reservoirs fluctuate easier
• Large reservoirs add stability for controlling temperature and other factors
• PPM, EC and pH are easier to control in larger tanks

4# Top Off Your Solution

If you need a quick fix, then this can suffice to drop your temperatures down a few degrees on hot days. This method shouldn’t be used too often because either you will be diluting your nutrient mix, or you will be using more nutrients than you need to.

It is better to use this method in case of emergencies because if you have temperature fluctuations, they will always be there, and this method doesn’t do much to eliminate them.

• Not to be used all the time
• Add cooler solution slowly so not to shock plants

5# Bury Your Reservoir

This method only works if you have an outside hydroponic garden. You can prevent several problems with your nutrient tank by burying it. This helps to maintain cooler temperatures but using the natural coolness of the earth, and it is sure to stop any light from entering your tank.

The main things to remember with this method are you may struggle when you come to flush your tank between growing. If it is already under ground level, you may not have a suitable drain point.

6# Make Your Own Swamp Coolers

Swamp coolers are effective, and very simple to make. All it requires is to take a suitable fan and blow this across the top of your nutrient solution. As a result, you may see temperature drops of around 5 to 10F.

The downside to this is you can be topping off your reservoir more often to compensate for evaporation. Second to this, your EC and PPM levels will rise that will require continual adjustment. You may also find using this method, you are allowing light into your tank.

7# Make a Cooling Coil

While these can be effective, they do take more work and they have the downside of wasting water. To make one of these, you can take copper or stainless steel tubing and form it into around 20 coils. This will then sit inside your reservoir with a hose connected to both ends.

One fits on the faucet while the second drains. In operation, the water trickles through the tubing and will pull heat from your reservoir into the liquid inside.

• Wastes water
• Can offer unlimited cooling at a cost
• Doesn’t need any power

8# Buy a Water Chiller

One of the most efficient ways to cool your reservoir is to purchase a water chiller. These deliver a hands free approach and give you lots of control. These do become more cost-effective if you have more than a couple of tanks where you need to control the temperatures.

These water chillers can be a hefty investment, and they do consume electricity for their operation. There are varying sizes so scaling up to any sized garden can be straightforward.

• Most expensive option
• Still requires water pumps
• Can be a set it and forget it solution
• Ideal for larger gardens

Ideal Hydroponics Temperature 

Plants thrive better when they are in a constant environment. While nutrient temperature can fluctuate, the main problem can stem from the grow room itself.

For ideal temperatures for good plant growth, the surrounding environment should be around 70 to 80F. For optimum root growth, the ideal temperatures of the root zone should be around 66F. 

Once the temperatures are above these, then stress starts to show in your plants. Heat stress can cause plants that are spindly in the early stages of growth, and mature plants can fail to fruit or flower correctly.

Most of the above methods focus on cooling a nutrient mix which is already warm. However, to have the perfect grow room will mean that your tanks temperature doesn’t climb in the first place.

Here are some of the best ways you can help maintain your grow room environment.

Air conditioners: This works as well as a water chiller, but for the surrounding environment. The environment will warm because of grow lights, or any natural light, which spills in through windows. You can purchase window type air conditioners that are ideal to cool your grow room enough without breaking the bank.

Relocate or Insulate Grow Rooms: The biggest culprit for tanks heating up will be your grow lights. If your grow room faces the south, or your grow room is under a hot roof, you may be fighting a losing battle with your tank temperatures.

Insulating your grow room can prevent hot weather having an impact. Additionally, if you can move a grow room into the basement, you will find it is naturally cooler than above ground level.

Increase Humidity: If your grow room suffers from low humidity, then your plants will take up more water to keep cool. This is where your tank levels drop faster and thus warm up quicker. Misting your grow room can keep plants and the surrounding areas cool, and as a result, your nutrient mix will remain stable.

Improve the Air Flow: Plants require good air circulation for healthy growth. This will also help prevent your nutrient mix from warming in the first place. Plants will benefit with circulating air, and it stops pockets or warm zones from forming around the grow room.

Run Lights at Night: One-Way of cooling a grow room which many growers often overlook is using their grow lights at night rather than in the day. Using supplemental lighting at night not only offers cheaper electric in some cases, but a grow room will be cooler at this time. The overall temperature of the room may not reach a level that will push your reservoir up to the higher limits to cause problems.

However, doing this will mean you need alternative counter measures in the day to cool your grow room. This will depend on the location as to the extent you need to go. If your grow room has access to natural light, it can be just a matter of extra shading, additional misting and fog to keep lower temperatures.

Calculating the Size of Water Chiller

One of the most crucial factors when choosing a water chiller is how well it will perform on your system. It isn’t just a matter of choosing one and expecting it to cool sufficiently. When it comes to the sizing of your water chiller, the following method allows you to determine the size of chiller unit that is sufficient for your garden system.

1. Calculate your system volume – this includes all buckets and tanks
2. Run your system with everything turned on – all grow lights, fans, etc.
3. When your grow room has reached its max temp, take a reading before cooling your system using ice packs or frozen plastic bottles of ice.
4. When your system mix cools, remove the ice and run for another hour.
5. After this time, take the water temperature
6. Subtract your ending temp from the starting temp
7. Use the formula to find the minimum BTU required.

• System volume: 80 gallons
• Desired Temp: 65F
• Running Temp: 76F

Formula: 80 x 8.34 x 11 = 7,339 BTU (gallons x weight of water x temporary difference).

A water chiller should run around 20% above your BTU requirement minimum to counteract performance loss.

Pros and Cons of Using a Water Chiller in Your Garden

Like many things for your hydroponics system, there are pros and cons of using a water chiller.

Pros of Hydroponic Water Chillers 

• Cooler temperatures enable your solution to hold a higher degree of dissolved oxygen. This is the key basis of increased nutrient uptake and explosive root growth.
• Highly oxygenated environments, which come with cooler temperatures, can help deter pathogens from taking hold.
• A cooler reservoir will act as a heat sink in your grow room. This can draw ambient heat and help to cool the whole room

Cons of Water Chillers in Hydroponic Gardens

• Expense is one of the largest primary cons for a water chiller. Although you can find affordable models, it can still be a cost that many growers can’t justify.
• Noise – in operation, these will sit outside of a reservoir like air pumps. They will make the same sort of noises as air conditioning units.
• Heat: Water chillers do generate heat when they cool water. Either they require ducting to transfer this heat out of the grow room, or they have to sit outside the grow room to not introduce more heat.

Why Do Roots Need Cool Temperatures?

Root zone temperatures affect overall shoot growth. Not only this, the impact from the root zone temperature will have more of a bearing on development and overall growth than the ambient air temperatures.

This occurs because the tissues of the roots send messages to the shoots. This will have an effect of how the shoot reacts to the environment. Growers see that there are many functions that occur for the plant in the roots, and thus, the root zone temperature becomes crucial.

Such is the effect of this, even thirty minutes of heat buildup in your nutrient mixture and in the root zone is enough to have a negative effect on your plants. One thing to note is that a daily cool average isn’t sufficient to counteract this.

As soon as your temperatures rise above 86F, then crops, which are sensitive to heat, will quickly falter such as lettuce or parsley.

When you look at something such as lettuce, the cooling of your nutrient reservoir does allow these crops to face higher than usual/ optimal temperatures above the surface.

While there are many biological happenings because of cooling roots lower than the ambient air temperatures, it is easier to know it reduces heat stress in the leaves of plants.

Root Zones and Different Hydroponic Systems

Cooling your nutrient solution to the optimal temperature isn’t all the equation. The remainder comes from the types of system you are running.

The root zone temperature needs to remain the same all the time. The cool mixture has a big influence on this, yet the system type and how it is built can affect this dramatically. A good example being the only system, which will have the same temperature root zone as the nutrients, will be a DWC system.

The roots are in constant contact with the solution. In all the other types of system, there is a degree of separation between the root zone and the reservoir.

A good example of how this can affect plants is in an ebb and flow (flood and drain) system. As your cool solution rises in the flood tables, the plants gain the advantages of oxygenated water and the roots are comfortable because of the lower temperatures.

However, things change as the cycle stops and the solution begins to drain back into the tank. Warm air from the grow room can be pulled through the growing medium as the solution drops. If the environment is warm, it can heat up your root zone considerably until the next flood cycle.

Unless you have a good means of cooling your solution, this will transfer heat back into your tank and thus warming it with each fill and drain cycle. Depending on your cooling solution, you may find that this is insufficient and as much as you are trying to cool your water, it increases in temperature regardless.

Not only will your water increase in temperature but also the root zone can be at a damaging temperature between your flood cycles.

Size of Your Hydroponics Reservoirs

One of the first things to be sure of is that you have a large enough reservoir. Rather than just being large enough for the size of system, you have, you are better to have a much larger one than you require.

Hydrotek, who are one of the largest names in hydroponic equipment recommend the following for reservoir sizes:

• Small plants – ½ gallon for each plant
• Medium plants – 1 ½ gallons for each plant
• Large plants – 2 ½ gallons for each plant

Hydrotek recommends you choose a reservoir that is at least double the size.

You also need to consider how thirsty your plants will be. This can use your water and nutrients faster, such as is the like of tomatoes in comparison to lettuce.

This will use your mix faster and thus cause a warm solution once the level starts to drop.

Using all the above information can help to maintain cooler temperatures for your nutrient solution. However, if you find your grow room comfortable for yourself as you are working in that environment, then you are halfway to knowing how it feels for your crops.

When new growers first start a hydroponic system, they often hear terms that sound confusing. One of the hardest to fathom is the pH, while you may not fully understand it in the beginning, it is something, which in theory can be learned quickly.

In summary, to keep pH levels stable, it can take a few steps and a little effort from the grower. These are the key areas you need to understand.

• Delivering the right supply of water
• Performing water treatment methods in response to the tested levels
• Understanding how the addition of nutrients can affect pH levels.
• Understanding what pH levels your given plants require

When you begin to understand what pH levels are, you quickly learn that they will never remain stable on their own accord. There are too many variables, and many external influences that will change the pH level.

It does take effort to monitor and alter your systems pH; however, this isn’t hard once you understand the core principles.

To know what pH means to your plants, and how it can affect their growth is the first area you need to understand. After looking at what pH is, we will see how it affects your system, and how you can maintain the correct levels.

What is pH?

First, up, there is a scale that runs from zero to fourteen. Every liquid will have a different reading against this scale. Plain water as an example has different pH levels depending on the source. Plain water from the faucet will have a different pH to the water in your system; this is because in many cases it is better not to use faucet water when possible.

This scale has zero, which is the most acidic, this runs up to the top (number fourteen), and this is the most alkaline. Most living things like a middle of the road balance, so this is around 7. Not only is this a good starting pH for most plants to thrive, but it is also the right level for the human body.

For plants to thrive at their best, they do favor pH levels, which sit around 5.5 to 6.5. Nevertheless, there are some plants and vegetables which like to go the other side of neutral to a pH of 8. Alkaline substances are soluble salts made up of potassium and sodium carbonate. Alkaline is the scale of the alkali within the solution.

When you have favorable pH levels in your system, this enables your plants to take up all the micro and macronutrients through the root systems. Add to this, you see faster growth in your plants because they have an increased intake of NPK (Nitrogen, Phosphorous and Potassium).

To go further in depth on this matter, you can head over to the pH levels Wikipedia page for a detailed breakdown of what these levels mean. This may appear interesting, yet it reaches a little outside what you need to know as a grower.

One thing, which is worthy to note, the closer you get to each end of the scale, and the liquids will burn. It doesn’t matter if it is acidic, or alkaline, so you will need to take caution when dealing with any pH level treatments.

Why pH Levels are Important in Hydroponic Systems?

We have seen when pH levels are outside the ideal range for your plants, they run the risk of not absorbing enough nutrients to help them grow. On top of this, it also helps you understand how soluble the salts are in your nutrient mixture.

Every mineral has a different tolerance when it comes to the respective pH level. As a rule of thumb, plants need high amounts of macronutrients. If the pH level is too high or too low, then these become immobile, and it is this that restricts their uptake, and leads to nutrient deficiencies.

Micronutrients on the other hand are required in smaller doses. These will be affected on either end of the pH scale. Once your pH is too low, then this means your plants can absorb too many as they are highly soluble. This doesn’t lead to nutrient deficiency; it actually leads to a solution that is toxic to your plants. If you go to a pH that is too high, then you will see a deficiency in micronutrients.

One of the first signs you need to be aware of is young foliage, which is yellowing or pale in color.

In order to keep the pH levels balanced in your hydroponic system, first, you really need to understand the elements that will affect the pH levels.

Growing Medium

Almost everything can affect your pH level in your system. One of the most significant areas will be your growing medium. A good example being calcareous rock, this will release magnesium and calcium into your solution. As soon as they leech into your water, you will need to adjust. Luckily, this isn’t a common growing medium.

Coco coir is very popular, and this can affect pH as they contain sodium chloride. Because of this, this needs to be soaked thoroughly to wash out any residual contaminants.

One other common growing medium is perlite. The pH of this is between 6 – 8, this means it can be added with no significant pH swings in either direction. Rockwool is another favorite and has a pH of between 7 – 8.5. This does require washing before use and an adjustment of the pH once it is in your system

Temperature

There is a lot to learn about solution temperatures, so without going into too much detail hydroponic solutions should be around 65 to 80 degrees Fahrenheit. If it gets much warmer than this, water starts to evaporate faster than the mineral salts.

One this happens, these begin clinging to the side of your reservoir, and thus increase nutrient to water ratio. You can also find that systems, which have smaller reservoirs, suffer more than a larger reservoir. Depending the region you live, you may require either a water heater, or a water cooler to keep your mix at the ideal temperatures.

Plain Water

Hydroponic systems need a sterile environment to function at their best. Water from the faucet isn’t recommended because of the amount of treatment it has been through. Different regions can have hard or soft water, so the base pH will never be standard.

It is a recommendation to use distilled or reverse osmosis water when possible. If this isn’t readily available, you can purchase these reverse osmosis kits which sit in your plumbing system. While these can seem to be a small investment, they can pay for themselves over time.

Here is an example of a reverse osmosis filter system. It can deliver pH neutral water for drinking, as well as for your hydroponic system.

Setting Up Your Hydroponic System Correctly

Now you understand all the reasons that pH levels are important to your hydroponic system, and the plants you’re growing, it’s time to test your pH levels and get your hydroponic system running before introducing plants into the environment.

If you are still researching, the following will still apply because pH testing isn’t a one shot thing. In the beginning, you can be doing this on a daily basis until you understand how your system works. To test your pH levels, there are various ways you can do this.

By the use of litmus strips, or digital testers, you can quickly find whether you need to adjust levels up or down.

One thing to note here is that some of the better hydroponic nutrients come with a pH buffer. This takes away any sudden level change to your plants. While you still need to adjust, the extent of what you do will be minimized.

Litmus Strips

Litmus strips are one of the quickest and simplest ways to test the pH in your system. Although they are easy to keep on hand, you shouldn’t rely on them without another means of measuring in place. The way these works is the paper contains a dye, which is sensitive to any liquid it comes into contact with.

To test your system, take a sample of your water in a sterile container. Dip one of the strips into this wait until the color changes. Once there are no more changes, you compare this against a chart, which comes with the litmus pH testing kit.

You may find some of the colors can be hard to distinguish from each other, so trying to guess which one it is, isn’t the best way to be safe. Many plants may not bother with this little difference, yet this half a reading in either direction can affect plants that require a tight tolerance.

You can also find liquid testing kits, which work in the same way. With these, you add the dye to your sample, and then once the sample finishes changing color, you compare this against your chart.

Hydroponic pH Pens

The most reliable option works out the most expensive, however, this is not overly expensive, and it can last much longer than your litmus testing kits. On top of this, you will have a digital readout, so there is no way to make a mistake.

One of the common designs is the digital pH pen. Once you place the nib in your water sample, you get an exact reading, which is precise. One downside with these is that over time, the readings may fluctuate, this means your pH pen requires calibration. If you perform lots of testing, this can be a weekly exercise.

We have written a complete guide to testing the pH of your water, we highly recommend understanding the full process to stop your plants wilting.

Continual Water Treatment and pH Balancing

Now you see the equipment you need to use to test your nutrient solution; we will look at how the varying hydroponic systems can have varying pH levels. One of the more straightforward are NFT (Nutrient Film Techniques) as your solution is in direct contact with the plants root systems.

Media based systems can have readings that vary one way or the other. It is for this reason; you need to take two separate readings. The first needs to be taken from your nutrient reservoir, and the leachate, which is the chemical runoff.

This is necessary because you will have different readings before and after the rooting system. This may not vary too much if you have smaller plants, yet larger plans will mean the variance is much higher.

When adjusting your solution pH levels, the base adjustments in the reservoir need to be adjusted to the readings you obtain from the readings you come up with from the runoff solution. The reason this needs doing is that your plant roots will be facing the pH levels in the solution, which passes them, and not the solution in the reservoir.

Adjusting Your Hydroponic pH Levels

Your pH levels rise and fall for all manner of reasons. Luckily, we have seen how easy it is to fix some of these. We also saw that your nutrients would come with pH buffers when you purchase them from reputable suppliers.

These buffers are a great way to prevent spikes or drops which may shock your plants. Aside from this, these suppliers also offer chemicals that you can use to raise or lower your pH levels. One of the more frequently used comes from General Hydroponics. These have pH UP and pH down you can purchase. Because of the pH sensitivity, you do need to follow recommended doses and take separate readings, in case you need to adjust again.

The aim when making your adjustments is to make sure there is no nutrient lockout. This takes daily readings to be sure your pH level is going in the right direction

When you come to make your adjustments, there are only a few steps you need to take to make these adjustments. The main thing is to be observant of what your readings are.

1. Take your first sample and then a reading Depending on the result you obtain, all you have to do is add between 1-2 ml of the pH Up or pH Down solution for each gallon of water you have in your reservoir.
2. Once you add this, stir your solution with a clean implement and wait a minimum of 30-minutes so the solution can run around your system. At this point, you can take your next reading.
3. You need to repeat these steps as required until you reach the required level. Never be tempted to add more of either chemical to reach the results faster. This will, shock your plants because you may swing too far in either direction.

When you add new nutrients, they will change your pH levels, which is why you will always need to do a new test once these have been added to the new reservoir. Other than that, it is recommended to run your tests more or less the same time each day. There are a number of natural approaches to tuning your pH if you have no pH Up or pH Down.

This is a very short-term solution and you should only use this if it is absolutely essential. Either white vinegar or citric acid may be used to reduce the pH, whereas baking soda is used to raise your pH levels. When doing this, you will need to know how much of a change there is for the amount you add.

Maintaining pH Level Recap

To summarize all the above, here is a quick recap of everything we have shown. Following these, you can maintain your pH levels and have plants that are continually thriving.

• Check your levels daily until you get to know your system. When you see how things are running, you can reduce your testing to 2 or 3 times per week.
• Even if you can’t afford the best testing kit there is, you should look for the best one you can afford. Litmus tests are handy to use, yet when you attempt to adjust your readings a few times, these are not as quick as pH pens.
• If you spot your pH, levels fall between 5.8 – 6.5. You should not be tempted to make any adjustments. This reading is ideal for most plants that you may be growing.
• Solutions which have a high pH need adjusting with pH Down.
• Levels, which are low, need adjusting with pH UP.
• Keep records of your testing and how much solution you add into your reservoir.

Overdosing with pH adjusters or nutrients is highly harmful to plants. On top of this, if you have a solution that drops in your reservoir, the pH change at the same time. Even topping up with water will have an effect, so be sure all your readings are when you have a full tank.

Growers who understand what their plants need, and how to adjust to keep them healthy will have some of the best crops when harvest arrives. Any grower who thinks this isn’t important may face a catastrophe.

There are so many options to support a thriving garden and hydroponics is one of the most recent systems I’ve read about. I’ve read that recycling hydroponic water can help save me money.

How to recycle hydroponic water: a beginner’s guide: Recycling water is a relatively simple process but can cost quite a bit of money between the initial investment and maintenance cost. You can use one of three main systems to recycle hydroponic water. Here’s a look:

• Pasteurization
• Ozone Sterilization
• UV Disinfection

If these systems sound as foreign to you as they do to me, I’m here to help. Take a look at a beginner’s guide on how to recycle hydroponic water.

The Importance of Cleaning Recycled Hydroponic Water

You’ll see many benefits from hydroponic growing but one thing you’ll quickly realize is that the system produces huge amounts of wastewater. Rather than just toss the wastewater (which is a bad idea anyway), many growers are starting to recycle their hydroponic water.

Recycling hydroponic water is a great idea. It cuts down on your water use and cost and helps prevent damage to the environment. That’s right, what’s good for your plants may not be good for the environment.

The nutrients that help your plants grown quicker than normal and produce more fruit can negatively affect the environment and groundwater that is turned into drinking water for humans.

Hydroponic solution is normally made up of at least a few of these nutrients:

• Nitrogen
• Phosphorous
• Potassium
• Calcium
• Magnesium
• Sulfur
• Iron
• Boron
• Copper
• Manganese
• Zinc

(If you haven’t read our articles about DIY nutrient solutions or if nutrients can go bad check them out)

Certain studies have found high levels of nitrogen and phosphorous in hydroponic water that was dumped. Those two nutrients, along with sunlight and slow-moving water, are what create algae blooms.

Algae blooms have a number of negative effects on our environment. Here are the four main issues:

• Algae blooms produce dangerous toxins that can sicken or even kill animals or people that come in contact with them
• Algae blooms create dead zones in the water. A dead zone is an area with low oxygen levels (low oxygen levels can lead to root rot). Eventually all the animals in the “dead zone” die.
• Consumers see higher treatment costs for drinking water affected by algae blooms
• Algae blooms hurt industries that depend on clean water.

While I’m sure you’re concerned about the effects on the environment, the other appealing reason to recycle your hydroponic water is the cost savings to you by not using as much water.

Plants grown in hydroponics already use 80 to 90 percent less water than standard plants grown in soil because the solution passes over the plants’ roots many times before you have to get rid of it.

Before you start reusing and recycling your hydroponic water, it’s important to clean and sterilize the water. It can carry bacteria, viruses, and other diseases. If you put this back into your system, you could potentially infect and damage your plants.

As I mentioned before, there are three main systems used for sterilizing your hydroponic water:

• Pasteurization
• Ozonation
• UV Disinfection

There are pros and cons to each system. Take a look at this table comparing the systems.

Now, that you’ve taken a brief look at the pros and cons of each system, let’s dive in and take a deeper look to figure out which system might be best for you.

Pasteurization

You might be familiar with the term pasteurization because it’s used in many of our everyday foods: milk, juices, egg whites, etc.

The process of pasteurization kills harmful, pathogenic bacteria. Removing the bacteria prevents diseases such as typhoid fever, tuberculosis, scarlet fever, polio, and dysentery.

Of course, these diseases aren’t an issue for your plants, but using pasteurization on your hydroponic water removes other bacteria that might harm your plants.

So, how does pasteurization work? Take a look at this process.

1. The used water is run through a 50-70 micron filter reducing the pH to 4.5 (learn how to monitor your water pH levels)
2. The adjusted solution is pumped to the first heat exchanger
3. This heat exchanger preheats the water while recovering heat from the sterilized solution
4. Sterilized solution leaves the first heat exchanger and is pumped into the second heat exchanger
5. An external heat source heats the nutrient solution to a certain temperature, ideally at least 203 degrees Fahrenheit
6. The nutrient solution is exposed to the high temp for at least 30 seconds
7. The sterilized solution is returned to the first heat exchanger to cool

It sounds complicated but you don’t actually have to do much.

As I showed in the table above, using pasteurization to sterilize your water prevents excessive mineral build up in the water, but can lead to mineral build up in the machine. This can decrease how well your machine works.

Your best bet to find a pasteurization machine for recycling your hydroponic water is in a specialty garden store or catalog.

Ozonation

Ozonation uses ozone to sterilize the water. Ozone is just oxygen with three molecules. During ozonation, the water is infused with ozone. The gas ozone is created by ozone generators in your grow room.

There are two types of ozone generators: corona discharge and ultraviolet. They work by splitting oxygen molecules into individual oxygen atoms. The atoms then bind to oxygen molecules creating ozone.

Here are all the steps to complete ozonation.

1. The water is filtered with a 50-70 micron filter.
2. Check the pH level of the water to make sure it’s between 4.0 and 4.5. This gives you the best results.
3. Your hydroponic water is pumped into the ozone generator.
4. The amount of ozone and length of sterilization depends on the level of nutrients in your water.

The benefits of ozonation as shown above are that it’s very effective and environmentally friendly. The downside is that ozonation can be costly and it’s highly corrosive so you have to be careful when dealing with it.

UV Disinfection

One of the final methods of high tech sterilization is ultraviolet or UV disinfection. UV radiation is part of the electromagnetic spectrum.

There are three types of UV radiation and they’re defined by frequency and wavelength. The best type of UV radiation for disinfecting your hydroponic water is UV-C. This type has the shortest wavelength and the highest energy.

UV-C radiation very efficiently kills bacteria, fungi, and viruses. Based on various studies, it looks like 250 millijoules per cubic centimeter is the appropriate radiation dose to totally disinfect the water.

Here’s a look at how UV disinfection works.

1. Pour the water into a disinfection unit.
2. The hydroponic water passes through a radiation chamber.
3. High pressure UV lamps contained in a quartz tube in the chamber disinfect the water.
4. A computer controls the process. If the UV dose is too low, the process is blocked and the water is returned to a drain water tank.

UV disinfection is pretty cost-effective compared to pasteurization and ozonation. It’s also natural. The only downside is that it doesn’t neutralize organics, chemical contaminants, or inorganic compounds in the water. This means it doesn’t remove heavy metals, salts, or chlorine that may have built up in the water.

Whatever sterilization method you choose, it’s essential to recycling your hydroponic water. You have to kill any destructive microorganisms that may have grown during the previous cycle.

Other Possibilities for Recycling Hydroponic Water

If the recycling options we talked about above sound like they’re out of your financial abilities or too much of a time commitment right now, you can consider just using the water on your other plants.

It’s important, though, to check the levels of the nutrients in your hydroponic water to make sure they’re not too high. If they’re too high, don’t use the water on any plants that are directly in the ground because the nutrients could affect your local water table.

A good way to check the nutrient levels in your hydroponic water is to check the potential (pH) and electrical conductivity (EC) levels. If these are within a certain range, your hydroponic water should be safe.

A good pH level is between 5.5 and 6.5. An appropriate range for EC levels is 1.2 to 2.0. You can read our full guide to EC and why you should monitor it here.

Plants in one study even showed better growth using recycled hydroponic water than those without. Here a look at the plants that performed well:

• Tomatoes
• Red peppers
• Cabbage
• Melons
• Cucumbers

There are a few other options for recycling your hydroponic water that you may hear talked about. While they have some effectiveness, they’re not recommended because none of them completely disinfect the water.

These are the other methods you might hear about:

• Ultra-filtration
• Hydrogen Peroxide
• Iodine

Ultra-filtration

Ultra-filtration is also known as membrane filtration. It includes the process of reverse osmosis. These types of filters have more porous membranes that allow solids, bacteria, and other large particles to be filtered out.

The main problem with this process is that the pores in the filter tend to clog making it an unreliable choice. The other problem is that the filters also remove fertilizer salts from the water, which are helpful for plant growth.

Hydrogen peroxide

Hydrogen peroxide works in much the same way as ozone does but it’s weaker. Because of this, it’s effective against fungi and viruses but not so much against bacteria.

If you recycle your hydroponic water but it’s not totally disinfected from the bacteria, you’re asking for trouble as soon as your plants touch the water again.

Levels of hydrogen peroxide that are too high can also damage your plant if they’re not neutralized before you return the nutrient solution to your plants.

Iodine

You may be familiar with iodine because it’s used in drinking water to kill human viruses, but it doesn’t actually kill horticulture viruses. This means that it’s not effective for disinfecting your hydroponic water.

Recycling hydroponic water back into your other plants still ends up saving you money and might even give you more plant growth.

A Key to Successfully Recycling Hydroponic Water

You can set yourself up for success in recycling your hydroponic water right from the start. Keeping your nutrient solution levels under control is key to extending the life of your hydroponic water before you even need to recycle it.

The best way to keep the nutrient level under control is to make sure you’re only putting in clean water. This means when the water level dips, refresh it with totally clean water. If you don’t, trace elements in the water will eventually accumulate to toxic levels.

If you were thinking you have to dump your entire nutrient solution any time the level drops, it’s time to do a little research. You can actually refresh the nutrient solution with clean water until you’ve replaced half of your system’s water capacity.

For example, if you have your hydroponic system has a 20-gallon water capacity, you don’t need to empty all of the water until you’ve replaced 10 gallons. This means that keeping meticulous notes is super important so that you do know when it’s time to recycle your water.

Rain water, city water, and well water are all possible options for clean water to replace water that is used. It’s always still important to do a water analysis, especially on city water and well water, to ensure that all elements are within a reasonable level.

Cities sometimes have to “shock” water with large amounts of chlorine to get rid of some sort of biological contamination. These high levels of chlorine can harm your plants.

Well water sometimes has very high levels of bicarbonates. Phosphoric acid is used to lower these levels, but sometimes a byproduct of the treatments is calcium phosphate. This can clog drip lines and submersible pumps and affect your nutrient solution.

You’ll quickly learn a key to success in hydroponics is very routinely analyzing the mineral levels in the water.

What Exactly is Hydroponics?

If you’re looking to recycle hydroponic water, I’m assuming you’re already aware of the ways of hydroponics. If not, though, I can give you a brief explanation so you know what you’re getting into.

Hydroponics is a way of growing plants in a water-based solution rich in nutrients. This type of growing doesn’t use soil, but an inert medium instead. An inert medium is one that doesn’t have any nutrients. Here’s a look at some possibilities:

• Perlite
• Rockwool
• Clay pellets
• Peat moss
• Vermiculite

Hydroponics works when the plant roots come in direct contact with the nutrient solution.

There are quite a few benefits to hydroponics. One of the main ones is that your plants grow quicker, up to 25-percent quicker. They’re also more productive, sometimes producing up to 30-percent more than plants grown only in soil.

The quicker growth and production happens because plants can access nutrients quicker and expend less energy. Because of this, they don’t have to grow a super big root system and can instead focus on growing quicker above the roots.

Along with the advantages of positive growth and production, hydroponic gardens do have some downsides. Here’s a look at some of them:

• Initial cost
• Time and commitment
• Technical knowledge
• Threat of power failure

Initial cost

You’ll spend some money upfront to get your hydroponic system up and going. You need containers, light, a pump, a timer, one of the growing mediums mentioned above, and nutrients.

Try to keep your initial investment under a few hundred dollars if you just have a small home garden. The good news is after your initial investment, your only costs are water and lighting.

Time and commitment

If you’re looking into hydroponics, you’re probably willing to invest some time in your garden. If not, hydroponics may not be the best choice for you.

You can’t just set up your hydroponic system and leave it. It requires monitoring the water level and the nutrients and adjusting the levels as needed. Unlike using soil, if the levels are off, the plants won’t just adjust to the changes, they’ll die.

You may eventually be able to automate your hydroponic system, but not initially. First, you need to get a feel for the needs of your plants.

Technical Knowledge

A hydroponic system isn’t just a simple pot with some soil. It requires putting the system together, figuring out which plants grow best with which nutrients, and making changes as needed. The elements are crucial to your garden’s success.

Threat of power failure

Finally, your whole system runs on electricity. This means if there is a power outage of any length, your system stops running. If the power doesn’t come back on within a couple hours, your plants will dry out and die.

A back up power source and a plan for if the power goes out helps minimize this disadvantage.

Despite the disadvantages, it’s worth giving hydroponics a shot. Eventually, you’ll save money and a great way to do that is by recycling your hydroponic water like we talked about above.

Hydroponic wick systems are one of the easiest hydroponic systems a grower can make and operate. Because of their simplicity, they are the cheapest to set up. These are fantastic for growers who are new to hydroponics, or for veteran growers who have spare space and wish to make full use of the area.

A hydroponic wick system can comprise as few as five individual components; this even includes your plants. Although, you can expand on this a little if you so wish. These systems are super easy to build and use, but there are some things to know along the way.

Here, we will look at all you need to know about constructing and running a hydroponic wick system.

Basics of a Wick System

In the purest form, all you need to build a wick system is a reservoir, your pot and growing medium, some nutrient solution and some wicking material. This can be strips of old clothes, rope or anything else capable of absorbing moisture.

The way these systems work, is by capillary action this you see in everyday life.

Here are a couple of examples of this in action:

• Clothes that draw sweat away from the body.
• Paper towels soaking up spilled liquids.

Plants do exactly the same thing, when their roots absorb moisture through the growing medium.

Capillary action occurs, because by essence, water droplets are sticky, so when they enter thin tubes (or porous materials) they start clinging to the sides of the tubes. Once this happens, something called meniscus occurs. This merely means there is a curved surface on the top edge of the water droplet.

Water droplets cling together through an internal bond of its molecules. This creates surface tension. With the sticky force of the droplet and the walls of the capillary tube, the droplets move upward. However, there are limits of how far this can travel in reality.

When you build a wick system, capillary action goes into action. The wick sucks water and nutrients up from the reservoir to your plants, as they need it.

Pros and Cons of a Wick System

Like any hydroponic system, there are pros and cons to each. Here are the upside and downsides of this simple system.

Pros

• A porous growing medium will increase oxygen absorption by your plants
• A wick system is very easy to understand and to build
• They are the cheapest to build and maintain
• Wick systems can be made from anything and will fit in the smallest of places
• Once running, they require very little maintenance or management

Cons

• Although a wick system can produce great results, yields can be lower than other systems
• Larger plants will require oxygenation of your nutrients
• You will need to change your solution to keep nutrient levels constant
• The likelihood of mold increases because the water is not circulating

One thing that links to the downsides, is plants, which are heavy feeders. These will take up more water, so your EC levels will rise. Not only this but also some large plants may take up water and nutrients faster than your wicks can deliver them to your growing medium.

These systems are more suited to lettuce or herb types of plants rather than tomatoes or peppers.

Components of a Hydroponic Wick System

Out of all the components in your wick system, the wick is crucial. The choice of material dictates how fast and how much liquid can travel through it to reach your growing medium.

Because there is a vast number of materials you can use, you can perform a simple test. If you place some food dye in water and then insert your material, you will be able to see how fast and how far it can travel.

This will give you an indication which material serves you the best. One other notable thing is to place two wicks for each planting area if you use larger buckets.

Items required

• A container or bucket for your plant
• A container or bucket for your nutrient tank
• A suitable wicking growing medium. Coco coir, perlite, vermiculite are ideal choices for this system
• Wicking rope or your chosen wicking material (about 2-3ft of 1-inch thick wicking material)
• 3/4 inch drill bit
• Electric drill
• Air pump and air stones – optional

Wicks – when you have your wick, you need to wash them beforehand as this can improve their performance. Depending on your system size, you will possibly require 2 to 4 wicks. The less distance water needs to travel, the better the performance of the wick.

Reservoirs – these can be any size as long as they are big enough to cope with your plants. There is a limit how small, but there is no real upper limit of size. They will require topping up with water so the end of the wick never sits above the water level. The closer the water to the top of your tank the better your wick will perform. Like other hydroponic systems, no light should be able to enter your water tank.

Air pumps – you don’t need the inclusion of an air pump, although, there is nothing wrong with adding one. This will increase oxygen, and it will help prevent nutrients from sinking to the bottom of your tank.

Growing Medium – You will require a growing medium that is capable of holding moisture. It can take some trial and error to find the right combination of wick and medium that work well together. If you find your wick is very efficient in soaking up moisture. You may need to add some larger growing medium like perlite or gravel to your initial growing medium to prevent over watering. Sand, coco coir or vermiculite are ideal mediums to begin with. 

Building Your Own Hydroponic Wick System

After looking at the basics of a Wick system, you will see they are easy to build with very few components. With that, we will now go through the building instructions. This will be using a 3-gallon bucket, but you can use any size as long as you have a second container suitable for your reservoir.

Tip: Two buckets of the same size are often used. One sits inside the other and rests against the side of the first, or rests on a brick that you place in your water tank.

Step by Step

1. Take your 3-gallon bucket and drill a 3/4 inch hole in the center of the bottom.
2. Fill your reservoir with enough nutrient solution so it reaches to just below your growing bucket once it is in place. Reserve one jug of your solution for the final steps.
3. Insert your wick through the hole and make sure it is long enough to reach the bottom of the reservoir. You will have around 1 foot inside your pot and 1 to 2 feet inside your reservoir.
4. Unravel your wick inside your growing bucket and then fill with your growing medium up to 2/3rds full. (Wicks need to be close to the plants rooting system, and long enough to be covered in solution as levels drop).
5. Insert your plant in the bucket and fill the top third of the pot with more growing medium or use Hydroton pebbles.
6. You can place your growing bucket inside your reservoir. It is advisable to make sure no light can enter where your nutrients are, because this prevents algae growth.
7. Gently top water around your plant with the solution from your jug. This prevents the growing medium from leeching moisture from your plant roots.

If you are using an air pump and air stones, all you need to do is make a small hole in the top edge of your reservoir and feed in the pipes (change clear for black tubing), this will add more oxygen to your water and aid in plant growth.

Maintaining Wick Systems for Optimal Performance

Wick systems require very little maintenance, but they do need some care an attention at some stages. A lot will depend on the size of your wick system to how much maintenance you do need to carry out. However, some of the principles are the same regardless of the size of system.

You may find plant growth slower than other systems. Nonetheless, there are a few things to help your plants along, like adding air stones.

These few pointers can help you get the best plant growth possible from this manual kind of Hydroponic system.

• Use multiple wicks so plants receive optimal amounts of water and nutrients – this will depend on your bucket size. Larger than 3 gallon buckets as in our example can use two wicks.
• Keep water levels as high as possible – the closer the water, the less distance it needs to travel.
• After harvest, be sure to rinse your growing medium and rinse off any salt build up. These levels will increase as your water levels drop. Only add enough nutrients and top off with plain water.
• You will need to measure EC & pH levels using your digital meters.

Conclusion

For some growers, they may think these types of systems are too simplistic and are unable to deliver the results they want. While these systems are simple in design and function, they are more than ideal for squeezing in small areas.

As for not delivering results, a Wick system is more than ideal for delivering great results for the right kinds of plants. This allows growers to free up space in a full system and use this system for plants that require less continual attention.On a last note, there is no other Hydroponic system that is more suited to new growers than these systems. They are the ideal training ground to learn all about hydroponics.