Tropical Aquarium Heater 75 Watt

Using 2 heaters is recommended for your aquarium which are equal to the total wattage required. So for example if you have a 100 liter aquarium and need to heat it from 18 degrees to 28 degrees (10 degree C increase) then the table recommends using a 100W heater. Provided you are using thermostat integrated heaters (of which most are these days) then you will not use up any more power or electricity as they wont be on for as long to heat the water. This is simply a precautionary measure in case one of the heaters fails, the secondary heater would still be capable of heating to the correct temperature, giving you time to purchase a replacement second heater.