Filling your tank up with water without knowing the proper wattage of heaters to use will get you into trouble. If nothing has been put in there yet, temperature could be wrong and potentially hurt whatever you plan to stock it with. Most new tank failures is not because of filtration but heating issues. Heating a tank are very important and something that you should pay close attention to so that you don’t burn through your electric bill in the winter or kill your fish.
According to this rule of thumb, use three to five watts of heater power per gallon of water. Depending on size of your aquarium, the room’s ambient temperature, and where you live, that number may shift. The warmer the room, the fewer watts required; the colder the room (or draftier), more watts needed.
How to Choose Aquarium Heater Wattage
The bigger the tank, the lower wattage/gallon requirement because a large tank hold heat better then a small one. So in other words, upgrading to a larger tank means you actualy need fewer watts per gallon because they holds heat better.
Wattage is important but so is what kind of heater you have. Inline heaters that plugs into filter tubing keep your equipment hidden. Submersibles that hide behind decorations provides even heating. Hang-on models can come loose from their suction cups and aren’t very accurate.
In large tanks use 2 smaller heaters rather than a single large one. If one goes bad you still have the other to maintain temp until you can get the broken one replaced. A heater should of be located close to output of your filter (away from any hot spots). Water exiting the filter will distribute warm water rapidly and protect your fish from being burned.
A digital thermometer with its own readout is necessary as well since the dial on a heater can be wildly inaccurate. A thermostat’s internal heaters can drift as well. Using an external temperature probe allow you to read the actual water temperature. It’s worse for the fish if the temperature changes suddenly rather than staying at a steady wrong level. Temperature changes are far more worse then a constant wrong temperature. Rapid change or “shock” temperatures is impossible for fish to acclimate to fast enough to survive.
Aquarium heaters will last up to 2-3 years, but eventually their parts wear out, and they may fail at any time. That’s why changing them regularly is important for safety. First, turn off the heater and allow it to sit in the water for a half hour before pulling it out. If you pull a glass heater out of the water too soon and it cools rapidly in surrounding air, it could shatter, making this process hazardous.
If you do all this properly, then your fish will live in a safe and stable environment. They’ll thrive in clean water and you’ll have an ecosystem that works well, no more stressed-out fish!