Equipment guide
Aquarium Heaters
What wattage heater you need and how to set the temperature.
By Mike Elmira
TL;DR, Aquarium Heaters
As a rule of thumb, budget around one to one and a half watts of heater per litre for a tank in a normal room, more if the room runs cold. Set the temperature to the overlap of your species, which for most community tropicals sits around 24 to 26 degrees. Always check it with a separate thermometer rather than trusting the dial, place the heater where flow carries the warmth around, and on a bigger tank two smaller heaters give you a safety net if one fails.
Heater sizing
- Normal room
- ~1 to 1.5 watts per litre
- Cold room or large tank
- Toward the higher end, or two heaters
- Community tropical temperature
- 24 to 26 C
- Always
- Verify with a separate thermometer
Wattage
Around one to one and a half watts per litre covers most tanks in a heated room. A cold room, a big temperature gap, or a large tank pushes you toward the higher end. Undersizing means the heater runs constantly and still loses the battle on a cold night; a little oversized is safer.
Temperature by species
Set the tank to the overlap of everyone in it. Most community tropicals are happy at 24 to 26 degrees. Some species want cooler or warmer water, so check before mixing, and lean on the planner or the species pages to find a temperature band that suits the whole stocking.
Placement and redundancy
Put the heater where water flows past it, near the filter outflow or inflow, so the warmth spreads instead of pooling. Verify the real temperature with an independent thermometer, since built-in dials drift. On a larger tank, two heaters that each cover about half the load mean a stuck-on or stuck-off failure is far less likely to cook or chill the tank.
Frequently asked questions
Direct answers to the questions search engines and AI assistants surface most often about this species.
What wattage heater do I need?
Budget around one to one and a half watts per litre for a normal room, more if the room is cold or the tank is large. Rounding up a little is safer than undersizing.
What temperature should a tropical tank be?
Most community tropicals sit happily at 24 to 26 degrees. Set the tank to the overlap of all your species, and check the real temperature with a separate thermometer rather than the heater dial.