What Size Aquarium Heater Do I Need?

A general guideline suggests applying 5 watts (W) of heat per 1 gallon of water when two conditions are met: a) the intention is to elevate the water temperature by 10 degrees above room temperature, and b) an aquarium lid is employed to conserve warmth and counteract evaporative cooling. For instance, if you have a 29-gallon tank meeting these criteria, it's advisable to use a heater with a capacity of 100 watts. However, in instances where your dwelling tends to be colder, around 65°F, and you aim to increase the water temperature by 15 degrees, it's prudent to contemplate adding a secondary heater.

Several other elements influence the temperature of a Fish Tank, including its placement within your residence. Whether it's situated in a sunlit room, the basement, or near an air conditioning unit affects its temperature. Additionally, due to the natural upward movement of heat, tanks positioned lower in an aquarium stack will be cooler than those at the upper levels. Moreover, equipment such as lighting and filtration plays a role in the overall heat generated within the aquarium.

For larger tanks requiring 200 watts of heat, it is advisable to acquire two 100W heaters instead of a single 200W heater. Employing multiple smaller heaters mitigates the risks associated with equipment malfunctions. If one heater were to become excessively hot, it is unlikely to singlehandedly overheat the entire aquarium. In the event that one heater malfunctions, the second heater serves as a safeguard, preventing the water from becoming excessively cold.