How to Keep Aquarium Temperatures Constant

Reef tanks sometimes need a heater and chiller to keep temperatures consistent throughout the year.
i Jupiterimages/ Images

Sharp temperature fluctuations might be uncomfortable for you, but they're downright murder on your fish -- even on your aquarium plants and corals. In most cases, maintaining consistent aquarium temperatures calls for a heater and adjusting the environment your fish are in. But some tanks need a little extra.

Defining Consistency

All aquarium inhabitants, from fish to corals, thrive in specific temperature ranges. If your tank temperature fluctuates above or below their preferred range often enough and for long enough, the life forms in the habitat will become stressed and can die. As long as you're within the appropriate range, the suited tank life will live just fine. Think of a consistent temperature as a range of degrees rather than one specific figure.


Tropical aquariums need supplemental heat. Tropical fish need a temperature between 75 and 82 degrees Fahrenheit, which is warm enough to require a heating source. Modern aquarium heaters are fully submersible; they suction-adhere to your tank's glass. You either turn a dial or tap a few buttons to maintain a temperature.

Fans and Chillers

Unless you live in Eskimo territory and don't have a furnace or inside heat source, you typically won't need to cool your aquarium unless you run a cold-water tank or a reef tank. Reef tanks use hot-running lights and other hardware that sometimes necessitate the need for a cool-me-down. Chiller units and cooling fans reduce tank temperatures for cold-water creatures. Chiller units are expensive. You can sometimes keep temperatures consistently below 80 degrees with the use of aquarium cooling fans. If the fans aren't working, or if you run a cold-water aquarium, you will need to invest in a chiller system.

Environmental Conditions

Keeping your home's temperature consistent year-round aids maintaining consistent tank temperatures. Placement of your tank also plays a factor. Keep your tank away from windows, drafty areas and naturally cooler or warmer areas of your house, such as your basement or attic. Don't let sunlight fall on the aquarium -- not only will temperatures fluctuate, you'll also have increased algae.

the nest