One or 2 heaters, that is the question

[fishy_jim]

Do you all think 2 - 250W heaters would suffice for an 80 gallon?

[jwcarlson]

I would assume it would be more than enough unless you're crazy like me and you let it get down to 55 in the winter and run the discus tank at 85, then it might take more. But in most every situation, I would imagine you could even go a little lower.

[fishy_jim]

Thanks all - 2 Cobalt heaters and inkbird w/wifi ordered

[Red Eye.]

I find it's less the size of the tank then the temperature difference between the room and the tank temperature. Jacob cites an extreme case with 600W total for a 75 gallon tank in a cold location. I have a 125 gal tank sitting in a walk-in closet adjacent to my bedroom. It has 1 X 100W and 1 X 200W and the larger heater (which I set 2 degrees warmer) only comes on during a big water change. For esthetic reasons, my heaters are on the same side of the tank occupying different walls, but I have very good flow in the tank. My recommendations are as follows:

1. Always use 2 smaller heaters vs 1 big one.
2. Set one 1 - 2 degrees warmer than the other one.
3. Use different wattage heaters for maximum flexibility.

If you're looking for controller recommendations - Inkbird controllers have been rock solid for me.

Wrapping your tanks with insulation is a best practice regardless of the cost of electricity. More stable temperatures will produce better fish. In addition to the wrap around, all my tanks sit on a 1"-styrofoam board from Home Depot.

How about under tank heating... slight heat like under floor heating....

[AquaticNerd]

I don't think I'd risk an under tank heater. I'd be afraid of its ability to control water temperature accurately (suppose you could get around it when paired with a controller). On top of that, what happens when the heater inevitably fails? I'd much rather just quickly swap a heater that is submersed than have to go through the rigamarole of emptying the tank, lifting and supporting it, and replacing the under tank heater. Another thing I'd be concerned about is bottom glass - we all know glass is an insulator, and the heat transfer from the bottom of the glass to the top of the bottom glass to get heat into the water seems like it would not only be wasteful, but prone to creating cracks and failures due to the repeated heating and cooling of the tempered bottom glass panel.