Your aquarium will require a heater to keep the water temperature consistent and provide the optimum conditions for your fish and plants. Like most aquarium equipment, heater types vary in size, efficiency and performance.

Heaters vary in size, wattage and components such as the heater core and heating element. In general, you will need 3 to 5 watts of power to heat each gallon of water. A 50-gallon tank will require a heater of 150 watts or slightly larger. A 100-gallon tank will require a heater of 300 watts and so on. Very large tanks may require more than one unit. When shopping for heaters consider several factors. Heaters are generally of two types, submersible and over-the tank.

Submersible Heaters. These heaters are slimmer and less noticeable than the over-the-tank types. They come in a variety of lengths to accommodate deeper tanks. Their main advantage is that they are sealed to prevent water from seeping into the chamber that houses the element and heater core. They are held in place on the tank wall by a suction attachment and can be camouflaged by plants or rocks.

Over-the-Tank Heaters. This type of heater is clamped to the tank wall by a plastic screw that holds it close to the rim of the tank top. The heat control is protected under a plastic cover that prevents the heat setting from being accidentally changed.

Both types of heaters come with the option of a thermostatic control. This is a great advantage for maintaining proper and steady temperature. Like a household thermostat, you can set these heaters to a specific temperature and it is constantly maintained. Non-thermostatic heaters have to be monitored for temperature regulation and will vary more in performance.

Using a Heater

Before you plug in the heater, let it sit in the water for 15 to 20 minutes to acclimate to the tank temperature. Heaters are marked with a minimum water depth line. Make sure the water in your tank reaches this mark or you may risk damage to your heater, tank and electrical injury. Once you plug the heater in, a small light indicates it is working. When the light goes out, it means the temperature setting has been reached. For heaters with no thermostat, you will need to check the temperature and make adjustments up or down as desired. All aquariums should have a thermometer for monitoring temperature even if your heater has a thermostat. A plastic heater guard will help protect your fish, plants or invertebrates from heater injury.