Selecting the Proper Heater for Your Specific Application

How do you select the right heater for your aquarium? There is an easy rule of thumb that should be used when you decide to build a tank. Choose a heater that would is between 3 to 5 watts per gallon of water that will be in the tank. Base your decision on the aquarium size and not the net amount of water, after all gravel and other features will need to be heated too.

Example: a 90 gallon aquarium would need a heater between 270 watts (90 x 3) and 450 watts (90 x 5). Since most heaters are usually manufactured in 50-watt increments, your selection could be any one of the following: from 300 to 500 watts. A good choice would be to use 2 heaters that would total up to the upper limit. Hence, 2 - 250 watt heaters would be good. This creates a safety valve. If one heater fails, the other would work overtime but would be able to handle the aquarium needs AND if one becomes stuck on, it would take quite a bit of time to overheat the tank.

You will also need to decide on heater styles - hang on tank or submersible. Frankly, it is a matter of personal choice and decoration needs. What we did for our saltwater tanks was to hide submersible heaters in the sump filters. The tank does not have the electric cord hanging down into the water and the filter keeps water flowing around the heaters. We have had no issues with temperature control.

The chart below should help in making a quick decision   

 

There are variables that can effect your aqaurium temperature conditions. Halide and compact lights can heat up water as can a closed hood that holds in the temperature. Other variables include where the tank is positioned. What type of room will you put it in? Sunny and warm or shady and drafty? Will it be by a heater/air condioning unit? We have a 210 gallon tank in a cool room on the north side of the building, however, the tank has fairly heavy lighting and multiple pump units to create water flow. Our problem is actually keeping the temperature down. The 2 heaters we have are rarely on!!

If you are putting the aquarium in a cooler room, choose a wattage on the higher end and watch. You may need to step up the wattage if you cannot maintain a stable temperture range for your fish. Try keeping the hood down - that will help keep the heat in the tank and not dissipating into the room.