An Aquarium Chiller Can Save Your Fish Tank in a Heatwave

An aquarium chiller is a game-changing revolution in the hobby, and it is hard not to get excited about it.  In the wild, fish can swim to warmer or cooler waters depending on their preference.  Our fishy friends don’t have that option, and even the smallest increase in temperature can kill them. 

Even though fish tank coolers are important, not all fish tanks need them, and the capacity of cooling is not determined by the size of your fish tank but by the inhabitants and your cooling needs.  We reviewed 4 of the top aquarium chillers and a cooling fan, which may be more suitable for some aquarists.

If you are a handyman, we will teach you how to build your aquarium cooler and for everyone how to set one up. 

Why Use an Aquarium Chiller?

It would help if you had an aquarium chiller because an increase in the heat of your fish tank can spell trouble for delicate pets causing less dissolved oxygen and encouraging the growth of bacteria in both fresh and saltwater fish tanks.  And for those with reef tanks, the increased evaporation may lead to toxic salinity levels.  All these problems disappear with a simple device that cools water before reintroducing it into your fish tank.

Essentially a fan can do this too, but what makes an aquarium chiller a powerful tool is that you can use it to create a symbiotic relationship between your heater and fish tank cooler.  As the aquarium water rises above a specific temperature, the thermostat of the heater turns off, and the aquarium cooler turns on to keep your aquarium within the perfect temperature parameters without you even having to be there. Could you ask for more?

If you need help choosing the correct heater, check out our article How To Choose The Best Aquarium Heater In 2020

When Do You Need a Chiller for an Aquarium?

It is true not all fish tanks need a cooler, but many fish tanks will thrive with this addition and make your life stress free.

An aquarium chiller is a perfect addition for delicate fish tank inhabitants like corals, shrimp, crabs, and countless others who tolerate narrow temperature changes.  Breeding and coral tanks need to remain not only stable but perfect, and we are now able to keep these temperatures under precise control.

An aquarium cooler is an essential component if you are taking the path less traveled, ditching tropical fish for their coldwater counterparts.   If you are planning to keep trout or bass in warmer climates, you may need to invest in an aquarium chiller.

SIDE NOTE:  Coldwater aquariums are not recommended for newbies to the hobby unless the temperature parameters match the climatic conditions in your area.

Fish tank coolers are essential for hobbyists who reside in areas where the summer temperatures spike or where central cooling of a non-tropical fish tank is not the best option.  A fish tank chiller keeps the temperature and, thereby, oxygen parameters stable within the habitat.  Fish tanks with powerful overhead lights and other heating elements will need a chiller for an aquarium to prevent overheating.

Selecting the Correct Size Chiller for an Aquarium

The size you need depends on the amount of heat generated from the various elements you have attached to your fish tank and the spring and summer temperatures where you live.  Fish rooms with central heating and cooling systems will require less cooling for fish tanks.

The larger the amount of water in the fish tank, although easier to keep stable, the longer cooling and heating will take; during a heatwave turning off lights and heaters may not cool the water fast enough.  Or worse, you may be on a summer vacation and come back to find your fish dead.

Monitoring the temperature fluctuation over a period of time to determine the amount of cooling you need from an aquarium chiller.

The material your fish tank is made from makes a difference; the glass tanks will keep the temperature steady for longer, creating a more stable environment vs. acrylic, which will be more subjected to heat fluctuations.   For more information on glass vs. acrylic aquariums, read our article, Glass Vs. Acrylic Aquariums – Which One Is A Better Choice?

Types of aquarium chillers include in-line and drop-in chillers. In-line chillers are easier to use and give you control over the temperature of the water you are adding to the fish tank, ideal for cool aquariums, whereas drop-in fish tank coolers are better for temperature control in a heatwave.

Different Aquarium Chillers for Sale

Keeping coldwater fish tanks is gaining in popularity but not to the extent that pet stores have aquarium chillers readily available; purchasing an aquarium chiller from amazon or similar online store is the best option.

With many fish tank coolers on the market, you need to consider the following factors before you decide which is the best aquarium chiller for your fish tank set up.  They will help you determine if your specific aquarium will need a chiller.  These are the elements to consider:

  • How much environmental heat is your fish tank subjected to
  • The temperature fluctuations during the year
  • The size and material of your fish tank and heat holding capacity
  • The heat generated from the external elements of your fish tank

The cooling capacity differs as wildly for the climate you are in and the type of setup you have.  This item can be costly, and purchasing with future planning in mind will save you from having to buy a larger system later.  

JBJ Aquarium Chiller

The JBJ Arctica Titanium chiller is a neat unit for large fish tanks, both energy and corrosion-resistant, perfect as a saltwater aquarium chiller. It is the quietest aquarium chiller on the market.  Easy to set up and use with three different hose connections to suit your current set up.  The horsepower options included 1/3, 1/5, and 1/10, accommodating to the heat generated from your unique system.


  • Retains memory after a power failure
  • Quick installation
  • Cost and environmentally friendly
  • The unit is quiet


  • The unit is large
  • Users have reported customer service issues from the company
  • More expensive than other similar size units

Our Verdict:  This fish tank cooler is ideal if your system has a sump or cabinetry to hide it in or a dedicated fish room.  The LED temperature controller is easy to read and adjust to the temperature setting you require.  This aquarium cooler has a memory recall function; you can rest assured your fish tank will be cooled even if you are away, and this makes it better than the Active Aqua AACH10HP Water Chiller Cooling System.

Active Aqua AACH10HP Water Chiller Cooling System

The Active Aqua AACH10HP Water Chiller Cooling System is perfect for a fish tank of up to 40 gallons of water. It can be used for both saltwater and freshwater fish tanks.  Horsepower capacity includes 1/10HP that can cool between 400-1060 GPH, 1/4HP that can cool between 264-660 GPH, 1/2HP that can cool between 350-850 GPH, and 1HP that can cool between 1320-3900 GPH.  This chiller is a large aquarium chiller you need to hide away, but for larger tanks or cooling requirements, this is perfect.


  • Cheaper than units of a similar size
  • Suitable for most aquarium setups
  • Cost and environmentally friendly
  • It is easy to use


  • The unit is large
  • Needs to be hidden unless you have a dedicated fish room
  • On arrival, this aquarium chiller had water in its pipe

Our Verdict:  This fish tank cooler for larger fish tanks and the LED temperature controller is easy to use.  Compared to the JBJ Aquarium Chiller, this machine offers more bang for your buck and is arguably more useful.  It had water in the pipes, but as all units must be flushed before use, one could overlook that problem.

Coralife Chiller

Coralife aquarium chiller is a popular choice; it is easy to install and use.  It has limited options as far as size and power output, but it has been well manufactured, and for the price, it’s something to consider, but if noise is your main concern, the  JBJ Aquarium Chiller is better.


  • Coralife has a good reputation
  • Ideal unit for larger fish tanks
  • Cost and environmentally friendly
  • It is easy to set up and use


  • The Coralife chiller is powerful but noisy
  • The bulky unit is hard to hide

Our Verdict: The appearance and size of this product beat the JBJ Aquarium Chiller, but if you are planning to use it in your living room, it isn’t quiet.  The company has an excellent reputation and comes in at a slightly lower price tag if you are on a budget.

Iceprobe Thermoelectric Aquarium Chiller

This Aquarium chiller is perfect as a nano aquarium chiller or a small tank that requires a slight temperature drop.  It lowers the temperature slowly over time, which creates a gradual change to the environment of your fish. 


  • Comparatively inexpensive to have as a backup
  • Quick installation
  • The unit is compact


  • Only appropriate for small fish tanks
  • Not useful as an emergency cooling system
  • No temperature controller

Our Verdict: A little fish tank chiller that is easy to hide in living rooms and bedrooms.  It doesn’t come with a temperature controller to balance it against your aquarium heater; you will need to purchase one to keep it functioning optimally, but it’s perfect if you need a low drop in temperature.

YueYueZou Aquarium Chillers Cooling Fan

If you need a chiller for 10-gallon fish tank, fans may be your only solution.  This fan draws wind across the fish tank cooling it by a few degrees.  YueYueZou cooling fans have the option of 1 or 2 fans.  Sleek black fans that can be added to the hood of any aquarium.


  • Easy to install
  • Two windspeed options
  • Adjustable bracket
  • Increases water surface


  • Increased water evaporation
  • This fan is a noisy product

Our verdict:  The increased evaporation is not ideal, but it is a problem with all fans, as is the imprecise temperature control.  Tanks with stable external climate control filled with hardy fish may not need a chiller.  The increased surface area increases oxygen levels, and this unit will lower the temperature of the water by a few degrees, and that may be enough.

How to Make a Homemade Aquarium Chiller

A DIY aquarium chiller may save you money, and you can find pieces that fit in the space you have available.  An aquarium water chiller is a refrigerator that cools water as it passes through the unit.  It is possible to build your own aquarium chiller with a garden hose and a small or secondhand fridge, but it will take time to play with the flow and thermostat settings to get it right. 

Factors to consider when deciding to build your own aquarium chiller are the longer water remains in the refrigerator, the colder it will become, and that without the thermal control, it can’t switch on and off like commercially purchased aquarium chillers.

Remove all the moving parts from inside the small secondhand fridge and drill two holes into the side. Don’t uncoil a new garden hose but flush the hose pipe with fish tank water and cut off the fittings.  Place the garden hose and push two ends through the inflow and outflow holes.  Run for 24 hours before attaching it to the aquarium.

After your DIY aquarium chiller has settled, you can attach it to the fish tank like any other fish tank cooler.  To find out which is the best silicone to use to create watertight seals, read our article Everything You Need To Know About Aquarium Silicone.

How to Set Up an Aquarium Chiller

Although there may be some differences between the devices, the setup is similar. The best place to put an aquarium chiller is in the sump or filtration housing or reservoir site, depending on the set up of your fish tank as long as there is enough space to allow the heat to dissipate from the cooler.

If you are using larger units in your living room without the cabinmate, hide it behind furniture or plants that will keep the unit out of sight.  They are silent enough to fade away into the background.

Attach the connectors and tubing to the intake valve and a submersible pump.  Connect the return tube to a u-bend pipe, which will flow cooled water back into your tank.  Clamp all the parts together and turn on the fish tank cooler.

Hold the increase button in for 5 seconds until it flashes.  Using the adjustable up and down, adjust the fish tank chiller to the desired temperature and touch the increase button to set the temperature.

For an automatic system, adjust the heater and aquarium cooler settings about a degree apart.  As the temperature of the water increases or decreases, the heater and cooler will turn off and on, keeping your fish tank at the optimal temperature year-round.

Always have an external thermometer to check both systems are in full working order.

Aquarium Chiller FAQ’s

Which Is Better a Chiller or Cooling Fan for an Aquarium?

A cooling fan is better for smaller fish tanks, hardy fish, and aquariums that have a stable external environment. In contrast, an aquarium chiller is better for corals and invertebrates or other fish that are less tolerant to heat changes.

How to Cool Down a Fish Tank

No matter what type of fish tank you have, you need to know how to cool down a fish tank without an aquarium chiller, to keep temperatures stable during heatwaves or other occasions where simply turning off the heater is not sufficient. 

As the temperature rises, this begins the oxygen depletion cycle; hot water holds less oxygen, increasing the stress to the fish, who use more oxygen when stressed.  Oxygen is going to become a serious issue very quickly.

In the wild, fish and other critters move to colder water if their current location becomes uninhabitable, and fish have not developed a natural cooling system of their own.  As aquarium owners, we have to cool down the environment.

An essential difference between lowering the temperature of your saltwater tank and freshwater fish tank with aquarium cooling the water from the ice or water bottles must not come into contact with the fish tank water.

The first step to cool down a fish tank is to be prepared by keeping bottles of RO/RODI water frozen.  In an emergency, add one bottle at a time to bring down the temperature of the fish tank. Complete a water change to decrease the temperature further and increase oxygen.

Turn off all lighting, heaters, and any element that produces heat around the fish tank to stop adding heat to the water.  Open the doors of cabinets with the filtration and hidden features.  Additional external cooling use fans or turn on air conditioning units (mobile units are available) to cool the fish room.

Side Note:  Even in an emergency, do not make any drastic changes.  Decrease the temperature slowly and deliberately. Sudden changes in temperature can cause gas bubble disease.  Add an air pump if oxygen has become an immediate problem.

Check out – BEST Quietest Aquarium Air Pump in 2020?

Summer Days No Longer Have to be Stressful

With an aquarium chiller, you can sit back in the knowledge that your fin pets are swimming around in ambient waters even if you are away on holiday.  If a power failure occurs, these fish tank coolers can be hooked up to a generator that will keep them running optimally.  Join me as we progress through the technological improvements that make fish keeping a breeze.

Also read – Is Aquarium Salt Necessary in Freshwater Tanks?

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