How to Keep Your Aquarium Cool


Apr 21, 2009
How to Keep Your Aquarium Cool
(or . . . Do I need a chiller?)

by staff
Reprinted with permission

For those of you (lucky people) that live in warmer climates, keeping your aquariums cool during the summer months is a challenge. The Aquarium Professionals Group receives dozens of calls each summer from concerned hobbyists seeking advice on how they can lower the temperature in their aquariums. Out here in the Chicago area, we've had reports of tanks running from the mid 80s to the mid to high 90s (Fahrenheit). In many of these cases, the aquarium owners do not have air conditioning in the room where the aquarium is kept, or they have no air conditioning at all. Out here, outdoor temperatures usually only get into the 90s from late June through August. Keeping the aquarium room cool is a first step, especially for marine aquaria. The cost of running an air conditioner for a few months is a small price to pay to keep our finned friends alive.

There are some instances however where air conditioning isn't possible, and what if air conditioning alone isn't doing the trick? The obvious solution is to add an aquarium chiller, but this is an expensive option. Even at internet and mail order prices, chillers can cost between $500.00 and $1800.00, depending on model and the horsepower needed. In some cases, a chiller is the only option, regardless of cost. This will depend on the type of aquarium you keep and the temperature drop needed to cool the tank. We'll talk about chillers a little more later, but first let's look at some other methods for cooling an aquarium during the summer:

How high temperatures hurt aquatic life. With fish, it's not always the high temperature that kills. Many fish die in tanks running too hot due to low dissolved oxygen (DO) levels in the water. The warmer the water, the less dissolved oxygen (DO) it will hold. This is also true for water with a higher density. A given volume of saltwater contains far less DO than the same volume of freshwater, so freshwater aquarium fish tend to tolerate higher temperatures because there is more oxygen available to them.

Other factors that influence whether fish will be affected by high water temperatures are the number (bio-load) and species of fish kept in the tank. The higher the bio-load in an aquarium, the greater the risk that oxygen will become depleted when the water gets warmer. If you have a fish-only tank (fresh or saltwater) and don't have air conditioning, keep your aquarium under-stocked! The species of fish are also an important factor. Freshwater Discus (Symphysodon sp.) thrive under high temperature conditions. Fish that inhabit warmer water in nature will obviously do well under those conditions in the aquarium (another good argument for designing the environment around the desired livestock when setting up a new aquarium). Keep in mind that we're only discussing fish right now. We'll get to live corals and other invertebrates later.

The ideal temperature for most fish-only aquaria is between 76 degrees and 82 degrees Fahrenheit. If you only have fish, the aquarium is stocked properly, and you only need about a 2 to 6 degree temperature drop, here's a few things you can try:

- Buy an air conditioner! Sometimes this is the only solution.

- Aerate with a strong air pump! This will help to increase the exchange of gases at the waters surface, thereby helping to raise DO levels. It will also aid heat exchange at the surface.

- If your aquarium is well-covered, open the covers on your tank, and place nylon netting over the openings to prevent fish from jumping out. This allows heat to escape. You can aid this process further by directing the air-flow of a small fan across the top of the tank.

- If your aquarium equipment is in a closed cabinet stand below your fish tank, open the cabinet doors and place a fan circulating air into the cabinet area to allow heat created from pumps to escape.

- Purchase a small canister filter designed with the motor on top (see our line of Eheim canister filters for example) and immerse the lower half of the canister in a bucket of ice to create a (relatively) inexpensive quick-fix chiller. Replace the ice as needed but please be careful! This method is tricky and requires some experimentation to prevent the tank temperature from fluctuating too rapidly (a major source of stress leading to fish diseases). Monitor the temperature of your aquarium carefully until you get the ice replacement times down to a science to maintain a stable temperature.

- Close the shades on windows in the room. Even indirect sunlight will raise the room temperature by a degree or two and every little bit helps. You can also reduce the amount of time the aquarium lights are on. The tank lights contribute greatly to higher water temperatures. Don't leave the lights off all the time though. That's bad for your fish too! If you have a freshwater planted aquarium, which requires at least 8 hours of light per day, you may have no choice but to buy an air conditioner or a chiller to solve your heat problem.

- DO NOT unplug your aquarium heater! This is a common mistake that often backfires. An aquarium heater that's working properly will shut off when the aquarium is at the proper temperature. Unplugging the heater could cause the temperature to drop too far at night in situations when it's hot during the day but cool at night and the windows in the aquarium room are kept open.

When a Chiller Becomes a Must-Have
Live reef aquariums and invertebrates:
Sorry folks, but if you can't use air conditioning and you own a marine live-coral reef aquarium, a chiller is your only option if the temperature of the tank is more than 84 degrees Fahrenheit. If you can have air conditioning but don't, get some! You don't have an option there either. Trust us when we say that replacing invertebrates that die in a hot reef tank is not only morally wrong and unethical, the cost of doing so will far exceed the cost of an air conditioner (and/or a chiller). If you are running air conditioning and your aquarium is still over eighty degrees, you need a chiller.

When it comes to keeping aquatic animals, our position is clear:
If you can afford to buy a nice aquarium, you should first make sure you can also afford to equip and maintain it correctly. In our opinion, a good aquarium chiller should be part of any live reef aquarium purchase, unless the aquarium will be kept in a room that remains very cool year round. This is also true for any specialized aquarium with lighting and pumps that create high aquarium temperatures.

If you do need to purchase a chiller, you may want to take note of these important tips. Remember that a chiller will emit quite a bit of heat. Do not enclose the chiller or place it inside a cabinet stand, unless the cabinet stand has been designed to house a chiller (a one foot square opening that matches the exhaust opening on the side of the chiller, and a one foot, fan-assisted opening at the other end of the cabinet for fresh air). Do yourself a favor. SAVE THE PACKAGING THAT CAME WITH YOUR CHILLER! You'll need it for at least thirty days from the date you bought the unit. Before you buy a chiller from a mail-order or discount internet source, make sure you know the return and service policies of the company with which you're doing business. Chillers can be easily damaged in shipping, and often that damage will not be immediately apparent. Chillers are heavy pieces of equipment and are expensive to ship. We've seen chillers that worked great for the first two weeks and then went kaput due to hidden damage to a relay or the compressor. It's worth spending more money to buy your chiller from a source that will help you if you have problems.



Author: Staff
Title: How to Keep Your Aquarium Cool
Summary: Summer temperatures can heat aquariums too high for many fish. Air conditioning is one solution, but there are some other techniques that can be used. Purchasing a chiller is an expensive option, but may be a necessity for reef tanks.
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Dec 26, 2009
i live in chicago and i found a neat way to keep my tanks cool in the summer i took a 5 gallon bucket cut a hole in the top for some tubing. ran the tube in a spiral into my tanks and added a a pump and the bottom. i added a a guge so that if it reaches above 85 it turns on. its only in my tank during the hotter weeks of summer. the buckett is in a old cooler and is filled with ice and water. i added some screen so the ice wouldnt go through my lines and into my pump. i also have a back footpump thats easiler put in because where i live the eletric goes out often in the summer.