Assuming now that you know what size of tank that you want or have,
we come to the topic of heating it. To keep temperatures tropical for your
aquarium fish, heaters have four basic parts - contacts, heating element,
indicator light and thermostat - all housed in a glass tube.
The heater's contacts are basically two pieces of metal that touch, completing the heating circuit to allow electricity to reach the heating element. Inexpensive heaters often have a flaw - contacts that melt together, overriding all thermostat controls and overheating aquarium water.
A heating element generally consists of an electrical wire coil around a ceramic insulator. When activated by contacts, the indicator light turns on and the element gets hot, warming the heater's glass tube and subsequently the aquarium water around it. Hobbyists who forget to turn their heaters off when making their monthly water changes will undoubtedly need a new heater. Exposing a plugged in unit to air generally results in overheating of the heating element and the breaking of the heater's glass tube.
Some heaters are submersible, and others are not. Personal preference should be your guide in selecting one or the other. Submersible models are nice because they allow hobbyists to hide the heating unit behind aquarium decorations. But hobbyists also should consider the amount of room they have inside their tank before selecting a submersible heater.
Traditional heaters that sit with their thermostat controls exposed at the aquarium's surface always are easier to adjust. They never require getting one's hands wet to change the water temperature. However, if your tank's backside already is overcrowded with external power filters and such, then a submersible heater may be your only choice.
A heater's size is given in wattage and is determined by the number of gallons of water an aquarium holds. For instance, a 10- gallon tank will need only a 50- watt heater whereas a 100-gallon tank may need two 200-watt heaters.
Both rambunctious hobbyists and fish can break the glass tube of an aquarium heater and thus render it unusable. Using a plastic holder to suction the heater to the aquarium wall will help keep the unit in place during normal operation. During tank cleanings, hobbyists just need to take care and not bump the heater against the tank glass.
The chart below will help you select the right size of heater.
|Size of aquarium||Wattage|
|Up to 5 gallons||25 W|
|5 to 15 gallons||50 W|
|15 to 30 gallons||100 W|
|30 to 45 gallons||150 W|
|40 to 75 gallons||200 W|
|55 to 100 gallons||300 W|