5 Best Water Chillers for Hydroponics

As hydroponic gardeners, we face all sorts of challenges when it comes to getting our plants to grow how we want them to, but none is more annoying than the dreaded overheating reservoir. While there are many different ways you can combat this problem, this article will give you an in-depth look at the best water chillers for hydroponics.

We’ll look at the three most popular brands, plus two alternative options that I’ve tested:

But before we get into the details, let’s take a look at what you need to know before you even consider buying a water chiller for your hydroponic garden.

Why Do You Need a Water Chiller?

Well technically, you don’t. There are plenty of other ways to cool down your reservoir if you want to save some cash. However…

High water temperatures are a consistent problem in many hydroponic setups, especially if you’re using a small reservoir in a system like deep water culture. The rising temperatures decrease the amount of dissolved oxygen around the root zone.

This in combination with the accelerated growth cycle of plants in a hydroponic environment usually results in oxygen deprivation. That means your plant dies. And dead plants are no good. Along with that, warmer water increases the likelihood that pathogens like pythium take root (pardon the pun) in your system.

A water chiller is one of many methods to cool down your system, but it’s by far the most effective. The only reason not to go for a water chiller is the price…it’s one of the more expensive solutions, but also one of the most effective and reliable.

What Size Water Chiller Do You Need?

If you’re set on getting a water chiller, it’s vital to know the size of your reservoir in relation to know what size chiller you need.

Here’s the best formula:

1. As accurately as possible, calculate how much water is in your hydroponic system.
2. During the hottest part of the day, turn everything in your garden that produces heat on. The goal is to let the room get to the max temperature.
3. Now, chill your system down to your desired temp (often 60-70F). Do this with sealed bags of ice or frozen two-liter bottles so you won’t be adding extra water to your system.
4. Once you reach your desired water temperature, remove the ice from the system and circulate the water.
5. Start a timer and write down the starting temperature.
6. One hour later, write down the current temperature.
7. Subtract your starting temp from your 1-hour temp and write it down – this is your temperature differential.
8. Now, use the following formula to calculate the BTUs you need:

Gallons of Water X 8.34 (weight of a gallon of water) X Temperature Differential

Now you know how many BTUs you need to adequately chill your system.

Example Reservoir Calculation

If you have a 75-gallon system, your max temperature is 80F, your desired temperature is 65F, and after an hour the water temperature is 70F…

75 X 8.34 X 5 = 3,127.5

Here are your conversions to the standard sizes that water chillers are sold in:

Tons	BTUs
1/10	1,200
1/4	3,000
1/2	6,000
1	12,000

It’s recommended to give yourself a bit of a cushion, especially when buying a low-end chiller. Typically, they won’t put out their actual power rating, so I would recommend adding about 25% to your total BTUs when deciding.

That means in the example above, you would want to boost up to the ½ ton chiller just to be safe.

The 3 Best Water Chillers For Hydroponics

1. Active Aqua Chillers

Active Aqua is one of the most popular chiller companies out right now. They have a variety of chillers, all with more or less the same features – the only difference is how powerful they are.

They all come with a microcomputer control system and LCD display which makes them really easy to set up and use.

Some of the common complaints about this brand is inconsistent build quality, meaning sometimes people are getting chillers that start to leak 6 months to a year into ownership and some people are getting perfect systems that are running without issues.

Other complaints are again in build quality, but more on the side of the temperature sensor.

• Build Quality: 3.5/5
• Effectiveness: 3.5/5
• Price: 4/5
• Ease of Use: 4.5/5

The Good

• Effective chilling capabilities
• Decently priced compared to most chillers

The Bad

• Some units have efficiency issues
• Slight cooling inaccuracies on the temperature sensor

Cooling Ranges

• 1/10 HP – Cools a 40 gallon reservoir by 15°F
• 1/4 HP – Cools an 80 gallon reservoir by 15°F
• 1/2 HP – Cools a 132 gallon reservoir by 15°F

Bottom line: if you’re considering an Active Aqua chiller, make sure you’re getting it from a reputable supplier. I’ve linked some below, but as always be sure to do further research for a purchase like this.

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2. Coralife Chillers

Coralife is one of the top names in aquarium chillers, making them a great choice for hydroponic environments as well. They’re one of the better-reviewed brands online right now, and seem not to suffer from some of the issues that I noted in my Active Aqua review.

All in all, these chillers provide accurate temperature control with the quality construction and durability. The included air filter keeps contaminants away from the cooling unit to ensure the efficiency and longevity of the motor. The air filter is also easily accessible and can be removed for cleaning.

• Build Quality: 5/5
• Effectiveness: 5/5
• Price: 3/5
• Ease of Use: 5/5

The Good

• Respected brand in aquarium products
• Build quality and reliability is high

The Bad

• Doesn’t come with a water pump or tubing
• More expensive than most brands

Cooling Ranges

• 1/10 HP – Cools a 40 gallon reservoir by 15°F
• 1/6 HP – Cools a 65 gallon reservoir by 15°F
• 1/4 HP – Cools an 80 gallon reservoir by 15°F
• 1/2 HP – Cools an 132 gallon reservoir by 15°F
• 1 HP – Cools a 400 gallon reservoir by 15°F

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3. EcoPlus Chillers

EcoPlus is another popular brand that’s been around for a while and is a favorite among both hydroponic growers and aquarium owners alike. One of the issues I ran into with these chillers was the fact that some portion of them are being constructed in China and the build quality has gone down.

I don’t think it’s a HUGE issue, but some people have reported that the Chinese versions of this chiller were lower quality, so watch out for that when purchasing.

Like most other chillers, they come with an LCD display and a reliable compressor that’s optimized for energy efficiency.

• Build Quality: 4.5/5
• Effectiveness: 4.5/5
• Price: 4.5/5
• Ease of Use: 4.5/5

The Good

• The most consistent build quality of all models tested
• Solid price points, not too expensive relative to other options

The Bad

• Be careful about Chinese knockoffs
• Doesn’t come with tubing

Cooling Ranges

• 1/10 HP – Cools a 40 gallon reservoir by 15°F
• 1/6 HP – Cools a 65 gallon reservoir by 15°F
• 1/4 HP – Cools an 80 gallon reservoir by 15°F

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Two Alternative Chillers To Consider

4. CoolWorks Ice Probe

I suspect that the CoolWorks Ice Probe may be the best choice for many hobbyist hydroponic gardeners (like myself). Unlike the previous options, it’s made for much smaller gardens and as such cools on a smaller scale.

The Ice Probe will typically cool a 10 gallon reservoir about 6-8F, making it good for “spot-fixing” smaller water temperature issues in most reservoirs.

In fact, some people use two of these and still come out spending less than they would if they went with a more traditional chiller design.

If you want the Ice Probe to trigger on or off based on temperature, you will have to use a separate temperature controller. Weighing in at only 2 pounds, the IceProbe is powered by a separate 12 volt D.C. power supply and draws less than 50 watts.

• Build Quality: 5/5
• Effectiveness: 3.5/5
• Price: 5/5
• Ease of Use: 4/5

The Good

• Extremely inexpensive relative to most chillers
• Doesn’t require a pump

The Bad

• Doesn’t turn on and off based on temperature
• May need more than one to satisfy cooling needs

Temperature Pulldown

10 Gallons	20 Gallons	40 Gallons
10-12°F	6-8°F	3-4°F

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5. iPettie Aquarium Cooling System

This is kind of a weird one to add in here, but I figured I’d give an option that was a little unconventional. This aquarium cooling system from iPettie functions as a sort of swamp cooler for your reservoir. You attach it to the top and blow air across the reservoir, cooling water as much as 5F from peak temperatures.

This makes it a good fit for people who just need to bring their temps down slightly during the summer months or a hot period.

You’ll need to make sure this will fit properly on your system since they’re made for aquarium setups. But I’m sure a little modification or tweaking would make it fit just fine.

• Build Quality: 3.5/5
• Effectiveness: 3/5
• Price: 5/5
• Ease of Use: 4/5

The Good

• Extremely inexpensive
• Easy to use

The Bad

• Only effective for specific cooling needs
• May not fit on some setups

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