Aquarium Chiller

by Aquatics on May 21, 2010

Written by Mike S. who works in Drs. Foster and Smith’s Technical Support Department.

Aquarium Chillers

Why Use an Aquarium Chiller?
In many aquariums, equipment such as pumps and lighting can create large amounts of heat to the point that it may affect the water temperature. Also, environmental conditions around the aquarium can affect this, especially in warmer climates. Not only can increased temperature create unwanted stress for the livestock, it can also reduce the water’s ability to hold oxygen. Using an aquarium chiller (or chiller) is one common solution to help prevent this from happening.

How Does a Chiller Work?
When people think of the word “chiller,” many think about a device creating cold air. The interesting part about chillers is that they are designed to remove heat, rather than directly create cold. The overall design of a chiller is similar to cooling configurations used in refrigerators and air conditioning systems. As the compressed gas refrigerant circulates through the unit, it picks up and transports heat from the aquarium water. Further cooling occurs when the gas refrigerant releases the heat to the radiator when the refrigerant pressure is dropped. Heat is then dispelled from the radiator by a fan.

fish-water-qualityHow Chillers are Installed
Typically, chillers are installed to an aquarium in-line with the existing filtration, or plumbed separately with its own pump. One of the major things to watch out for is the flow rate of the water being moved through the chiller. Manufacturers list minimum and maximum flow ratings for this. If water runs through the chiller too quickly, the chilling is not going to be effective. Too low of a flow runs the risk of the lines freezing up, possibly causing damage not only to the chiller, but also to other equipment in the aquarium system.

Another major consideration when installing a chiller is placement. Since the unit expels hot air during operation, the chiller will need to have open area (most manufacturers recommend leaving at least 12-18” of space around the entire unit). Additionally, the temperature around the chiller should be around 15-20 degrees cooler than the hot air coming out to ensure optimal performance. If insufficient ventilation is provided, the chiller may end up raising the water temperature due to overheating and recycling hot air.

Selecting an Appropriate Chiller
Factors to consider when selecting a chiller include tank size, flow rate of existing equipment, and climate conditions. In warmer areas, it is normally best to go one size up on the chiller to help make up for warmer temperatures that affect water conditions in the aquarium. Another factor that will prompt getting the next larger size is an aquarium with a canopy, as the enclosed setup will create additional heat.

Troubleshooting Common Problems
Chillers are designed to usually reduce the water temperature by about 10-20 degrees under optimal conditions. The compressor is the main moving part, and its noise level should be similar to a smaller refrigerator.

aquariumsIf the chiller is making loud noises during operation, it could be either the fan or compressor. To inspect this, the top cover sill needs to be removed to access these components. When a chiller ships, sometimes the manufacturer will keep a foam or wood block in front of the fan to protect it during transit. If this piece is still near the fan, it can get hit while the fan is running. Additionally, the fan blades should be inspected for any bends that may cause it to impact anything nearby.

If there is a loud banging noise during operation, the compressor may not be properly level, or the internal oil may not be set properly. To allow the oil to settle, the chiller will need to be unplugged and left to sit overnight.

A third common problem that can be encountered is the chiller not properly lowering the water temperature. This can be caused by hotter conditions in the aquarium, or if too small of a chiller was selected. If there is a canopy on the aquarium, the tank is kept in a warmer climate, or if metal halide bulbs are used, it is recommended to go with the next larger size chiller to compensate for the additional heat. As previously mentioned, ventilation can also play into a chiller not performing properly.

Chillers can play a critical role in helping provide the best possible environment for your aquarium inhabitants. A lot of the more advanced equipment available for lighting and water movement has the potential to heat up water, causing problems with livestock that are not able to adapt as quickly to changing water conditions. To help keep these problems in check, a chiller will help your tank keep its cool, assisting fish, corals, and invertebrates to live a longer, healthier, and stress-free life.

Browse for all your aquarium supplies!

Other Aquarium-Related Posts:

{ 1 trackback }

Tweets that mention Aquarium Chiller | Everything You Need to Know About Chillers! --
May 21, 2010 at 11:55 am

{ 7 comments… read them below or add one }

nyca May 21, 2010 at 7:59 am

Wow I didn’t know this.

Thanks for sharing!

john May 21, 2010 at 11:42 am

i have a chiller i need to get repaired…..i live in wisconsin and even in the summer my house temp doesnt get higher than 80 degrees so i can maintain my water temp where it needs to be without one….or should i have it regardless?

Mike S. May 21, 2010 at 2:59 pm


Thank you for your inquiry. To ensure that appropriate water temperatures are maintained within your aquarium system, it is still recommended to have a chiller running. In addition to environmental conditions near the aquarium, the use of pumps and lighting can still affect the water temperature. This is especially the case with metal halide fixtures, as they give off a significant amount of heat while they are running.

Mike S.
Technical Support
Foster and Smith Aquatics

Chau May 21, 2010 at 3:15 pm

Thanks for the great information. My tank and I are moving to a new location where temperature will fluctuates more often and a chiller might be needed over the existing fans.

Ron O. May 24, 2010 at 3:18 am

This will be my next investment. Good read. Thank you for the information.

Shannon May 28, 2010 at 8:14 pm

Great post! We invested in a chiller when we recently moved. Before we had lived in a house that had central air & we were able to keep the house & aquarium at a much more stable temperature. But now we do not have that luxury so upon setting up our aquarium again in our new place we invested in a great chiller. It has made such a difference & now that we are going into the warmer months we know that it will pay off by having it on the tank to control the temperature.

PW May 30, 2010 at 3:30 pm

All the very nice tanks I have seen have chillers. Lucklily my 125 gallon is in the basement so heat is never an issue

Leave a Comment

Previous post:

Next post: