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How do you cool hydroponic water

How Do You Cool Hydroponic Water? Follow These Hacks!

    Ensuring the reservoir water has the ideal temperature is the best way to keep hydroponic crops healthy. Usually, the water temperature continues to creep up due to continuous use. Especially if you are using an artificial lighting system, it is a huge issue. So how do you cool hydroponic water? 

    There are several ways to cool hydroponic water. You can either use dedicated equipment like a chiller or cooler which are specifically designed for cooling water or use scientific hacks like painting or insulating the reservoir to maintain the temperature of the water.

    Seven Hacks to Cool Hydroponic Water

    Depending on the size of the system as well as the room temperature, you will have to employ one or several methods together to cool the hydroponic water. 

    Ok, let’s examine the methods based on factors like ease of use, maintenance, and cost. This will give you a much better idea about these methods. I will also give you detailed steps to employ all methods for different types of hydroponic systems.

    1. Buy a chiller

    The sole purpose of the chillers to cool the solution like hydroponic water. You can achieve much more precise cooling than any other method. 

    They are the refrigerators of the hydroponic system which are designed to operate under the water. All commercial farmers like to use water chillers as they are a more cost-effective way and need very little maintenance.

    Probably the biggest plus that I believe of having chillers is that they are automation-friendly. If you use controllers for your hydroponic system, you can add a program to the controller for controlling the chiller.

    Ease of Use

    In order to use the chiller, all need is a power outlet for the unit. Once connected to the system all you have to do is set the desired temperature of the water and you are good to go. 

    All the chillers have different buttons and modes which you can take advantage of. With the simplest of the chillers like Active Aqua 1/2 HP, you get temperature buttons and power buttons. 

    So in terms of operating these chillers, you do not require any technical knowledge. But you must know what is the ideal temperature of water your crops need.  


    If you use clean water, the chiller hardly requires any maintenance. The only thing that you have to take care of is to never run the chiller without water supply. 


    When you compare the cost of a chiller to other methods to cool the hydroponic water, it is the most expensive one of all. However, I believe it is the most effective method.

    If you own a medium or large scale system, you want an effective as well as a reliable way to make sure you have the high yield. 

    Applying the method

    It doesn’t matter which hydroponic system you use, chillers work for all. Follow these steps to add a chiller to your hydroponic system.

    1. First cut off the water supply to the plant boxes or buckets by turning off the pumps and inlet valves.
    2. Connect the reservoir outlet to the chiller inlet. Use the compatible pipe size. 
    3. Now connect the outlet of the cooler to the inlet of the system.
    4. Open the inlet valves of the system, turn on the pump, and turn on the chiller.
    5. Make sure to set the ideal temperature on the chiller.

    2. Reflect the heat away from reservoirs

    If you ever paid attention in science class, you know the dark colors absorb heat and light colors reflect heat. You can paint the reservoir and the water pipes white or in reflective colors you can manage to keep the hydroponic water cool.

    Another way you can reflect the heat is by insulting the reservoir. You can cover the reservoir with insulating materials like Rockwool to keep the heat away.

    Ease of Use

    It is one of the easiest methods to apply. All you need is the right material or paint. 

    If you are growing crops in a grow tent or indoors with artificial lights, it is wise to paint or insulate water tanks. 

    In my experience, more than the weather the types of equipment used in the hydroponic systems generate more heat. So, using reflective paint or insulation keeps the heat away.


    Very little maintenance is required for this method. All you have to do is ensure the material used or paint applied is in top-notch condition.  You can make the entire method maintenance free.

    The best way to do that is to use high-quality material. Use heat reflective paints like elastomeric paints. They are easy to apply and require very little maintenance. 

    Only that you might find it concerning is the mold development overtime. This is the big reason why it is not considered a permanent solution.  

    The alternative thing to do instead of paint use reflective or insulating material like mylar, Polystyrene, or foylon. 


    If you look at the cost of both paints and insulation, it is around $30. Compared to methods like chiller or coolers it is cheaper. 

    But remember it is a temporary way to cool the hydroponic water. 


    You can check out  Jetcoat Cool King Elastomeric Acrylic which reflects almost 90 percent of heat. It works well on metal and plastic surfaces which is common for hydroponic reservoirs. 

    You can also use reflective material like mylar. Usually, the mylar is used to keep the heat within the grow tent. But if you use it on outer surfaces, it will keep the heat and light away from the system. The mylar has the ability to reflect almost 97 percent of the light. But it should not have any crease. 

    You can go for something like VIVOSUN Horticulture Highly Reflective Mylar Film Roll. You can trim the sheet as per the shape and size of the reservoir. 

    3. Increase the size of the reservoir

    One of the simplest methods to keep the temperature of a reservoir in check is to buy bigger reservoirs. 

    The bigger reservoirs have some advantages over the smaller ones.

    With smaller ones, there is too much fluctuation in temperature and nutrition mixture. You will have to make very minute changes in order to stabilize the temperature.

    However, the bigger reservoir temperature, pH, and ppm remain stable due to the higher volume of water.

    Ease of use

    Just buying a bigger Reservoir solves your issue. It is as simple as that.


    In my opinion, this is the best way to maintain the temperature of the reservoir without adding any additional cooling material or equipment. 

    All you will have to do is to maintain the right PH and the PPM level in the water. Also, clean the reservoir regularly to avoid algae growth.


    If you look at the cost of cooling equipment and water tanks for hydroponics systems there is a huge gap between the price. The tanks don’t cost much. 


    One thing that you have to look at while applying this method is the weather conditions of your location. 

    If you live in a cooler region, buying a bigger resolver is enough. But if you live in a hot region you will have to add additional cooling equipment. This method fails for the hotter regions.

    Once you are sure that you do not require any cooling equipment or material all you have to do is identify the size of the reservoir required for your hydroponic system.

    4. Top-off solution

    Not always you need a permanent fix. Sometimes you may want a temporary and quick fix. For instance, on hot days you may want to cool the hydroponic water to some extent. This method is perfect for such instances. 

    You don’t have to do anything. Just add a cooler nutrient solution to the reservoir and you are done. Let’s evaluate the method further. 

    Ease of use

    Adding water is a simple task but how much to add is the key. 

    With hydroponic systems, pH and conductivity are crucial factors. If you add more water you may reduce the pH or adding more nutrient mix can increase the pH. 

    So knowing what amount to add is the only crucial factor with this method.


    Adding water or a solution to bring down the temperature is all you need to do. However, if you look at the long run you will have to frequently add water depending on the size of the system. 

    Smaller the system, more frequently you will need to change the hydroponic water

    For this method, automation is not possible. You will have to manually add water based on the current water and ph readings.


    If you consider just adding water to the system,  this method has practically zero cost. However, if you like to add a nutrition solution or pH adjusters with water, you can expect a cost of $30-40.


    This is how you should add water to cool the hydroponic water:

    1. Measure the temperature of the water in the tank with a temperature. 
    2. Optional: you can also measure pH or conductivity if you like to mix nutrition to the top off water. 
    3. If it’s hot,  balance out the temperature by adding cooler water. 

    You can check out our post on how often to change the water in the hydroponic system if you want to learn more about this method.

    7. Fan Cooler

    If you blow some air across the surface of the water, the temperature may drop between 5-10 F.

    It is not a popular method because it is more of a DIY method and you cannot expect considerable cooling. 

    Ease of Use

    For this method, all you need is a table fan. But one main requirement of this method is you need an open tank or reservoir. 

    More the surface of the water is exposed more quickly you will be able to cool the water. 

    Since it requires an open reservoir tank we wouldn’t recommend a commercial hydroponic system. 


    You will have to continuously keep the fan on if the room temperature is higher than you need for the water. 

    In terms of maintenance,  just keep the fan at an optimum level. Clean the dirt on the blades regularly to have a nice flow of air. 


    A good quality table fan could cost around $20-30 but you need to also consider energy consumed by the fan. Though the table fan has 50-100 watt motors,  if runs for a month continuously it may cost you $30-40 on energy bills. 

    Overall,  it may seem cost-effective but it has recurring charges. I believe if you are willing to spend on recurring charges why not get a chiller or cooler which gives much better results. 


    This method requires two basic things:

    • Table Fan (minimum 50 watts)
    • Open reservoir.

    Also, you will have to store the water in different reservoirs from where you can pump the water to the crops. It is perfect for systems like NFT hydroponics as you already use different tanks for storing water. 

    To apply this method follow these steps:

    1. Take the table fan and keep the direction of the fan almost parallel to the surface of the water. You want the air to kiss the water, and not blow away the water. 
    2. One more thing you can do is stick thin frills, you can see the direction of the wind. Optional. 
    3. You can also direct the wind by sticking a piece of cardboard or metal sheet throughout the circumference of the fan forming a  wind concentrator. 

    6. Cooling coils

    Cooling coils are readily available in the market but you can also make one at home. You can use any copper or steel coils. Many expert hydroponic growers prefer steel tubes because they are corrosion resistant and also zero salt scale formation.  

    The way the method works is you make a coil out of these tubes and submerge in the reservoir. Keep both ends out. From one end you pour in cool water and the other end acts as an outlet. 

    While the cool water travels through the coil, it absorbs the heat from the reservoir. It is a simple principle of thermodynamics. 

    Ease of Use

    I would probably say it is the most tedious method of all. The reason is you have to constantly pour cool water through the coil. 

    For this method, you will have to create a constant supply of cold water. You can put a few bottles of water in the freezer and keep replacing them as one gets empty. 

    It is almost like a nurse changing the drip of a patient!


    As far as the durability of the material is concerned, the steel coil won’t be damaged. Yes, copper will change its color from brown to blue which means salts have made its permanent residence reducing the effect of thermal exchange. 

    As far as using the system is concerned, it is suitable for you if the temperature at your location rises only for a few days. 

    If the temperature is high for almost like a year or so, do not consider using this method. 


    You can buy any refrigerator coils. They cost around $15-20. Also, there is no cost as far as energy consumption is concerned. 


    Follow these steps to apply this method:

    1. Get a  20′ heavy-duty tubing of 3/8″ and also get a 1/2″ and 3/8″ brass hose to drain and inject the water. 
    2. Get a few 2.5-liter empty bottles. You can insert ⅜” hose in the bottle cap. Make sure it is tight. If possible use some kind of seal to avoid any leakage. 
    3. Now connect the hose to the one end of the coil. 
    4. Leave the other end of the coil open or into a tank to reuse the water. 
    5. Insert the complete coil into the solution.
    6. Hand the bottle just like the nurse does with a drop so that water can easily flow into the coil. 

    One thing to remember is to always use chilled water to make sure you can bring the temperature considerably for hot days. Some experts suggest freezing the water completely.

    7. Find the coldest Spot

    If the weather conditions are not that hot, just you want to keep the water cool during the afternoon when the temperature is at its peak, just find a cold spot at your location. 

    There is not much to do in their method. Just place your system somewhere in the shade. 

    Ease of use

    Usually, the basements have the coolest spots but you will require artificial lights for crops. However, you are not a fan of artificial lights, you can keep the system on a kitchen counter near windows. Also, make sure windows are either facing south or north to avoid direct sun over the system. 

    The idea is to save the system from heat. 

    You can also place the hydroponic system in a spot where there is a nice cool breeze throughout the day.  


    There is no maintenance required. 


    This method has zero cost. All you have to do is find the right spot. You can use a temperature gun or even a thermal camera to find the cold spot at your location. 


    While finding the cold spot you keep these things in mind:

    • Understand how much is the optimum temperature required for your plant. 
    • If you find the right spot, also check how sunlight the spot received throughout the day. 
    • You use it with other methods mentioned in this post to effectively cool the water of your hydroponics system. 

    8. Bonus Method: Get a reservoir made out of clay

    In Indian villages where there are no refrigerators, people keep their drinking water cool by using clay pots. They also cover the clay pot with a wet cloth which helps keep the temperature down inside the pot. 

    You can buy any type of clay pots or vessels and use it as a reservoir. 

    This could be a unique way of cooling hydroponic water.

    Final Words

    Don’t be confused about which method to use. Just ask yourself do you need a temporary fix or something you can rely on for a long period. And it is wise to use a combination of one or two methods to ensure effective cooling of hydroponic water.

    I personally prefer chillers because even if you change the size of the system you don’t have to change anything else for cooling the water. Yes, it has an expensive initial cost but it’s worth it if you are planning to scale up your hydroponic system. 

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