Using a Submersible Fish Tank Heater
Most of the fish commonly kept in freshwater aquariums evolved in tropical habitats over thousands of years. These fish are adapted to waters that remain in the high 70s to low 80s all year round. Even though these fish are kept in aquariums outside of their natural habitats, they fare best if kept in conditions that mimic their wild areas as closely as possible. In terms of aquarium temperature, this means keeping the water at a stable temperature. For most tropical fish, a fish tank heater can be used to safely keep the water at 80F.
Aquarium heaters come in two basic styles – hang on the back or submersible. Heaters that are made to hang over the back of the aquarium are generally cheaper in price, but they have limitations. The main disappointment with those heaters is that the top portion must be kept out of the water to avoid breaking the heater and possibly killing the fish. Hiding such heaters is difficult at best.
Submersible fish tank heaters are slightly more expensive but are much more convenient to use. Submersible heaters are able to be put anywhere in the aquarium – even right at the bottom near the level of the gravel. This means they can easily be hidden behind ornaments or aquarium plants. Having this style of heater means you can avoid having an unsightly heater in plain view in the fish tank.
Using the submersible heater is quite easy. Be sure to buy a heater (or combination of heaters) in the range of 5 watts per gallon of water. This must be done to make sure that the heater can adequately heat the full water column in your aquarium.
Before plugging it in, use the suction cups to place the heater in a location where it is conveniently hidden from view. I find the best spots to be near the bottom at the back of the tank. Make sure the glass of the heater is not touching any ornaments, aquarium glass, rocks, or other surface.
Let the heater acclimate to the temperature of your aquarium for at least 30 minutes before plugging it in. Plug in the submersible heater then let it run for 24 hours. After 24 hours, check the water temperature. If it is too hot, lower the setting; if too cold then turn the heater up. Check again after another 12 to 24 hours.