Originally Posted by HUKIT
I was curious if you were going with in tank heaters, my fish room consist of around a 1000g and I tried to heat just the room but eventually went to heaters in the tanks.
Heating the water directly with heaters in the tanks has to be more efficient than heating the room.
Water easily absorbs heat from the heater in it. If you heat air, air takes more energy to heat and is a better insulator than conductor of heat. On top of that, glass is an insulator too. So it takes a lot of energy to get the heat through the glass from the air in the room.
If you heat the water, you know the water is the right temperature. The task then is to trap the heat in the tank. Lids are very helpful. But eventually the room is heated by the water in the tanks. If insulated, the room then becomes very stable in temperature. If a heater is in the room, it just makes sure that the room temperature doesn't drop (on very cold days) enough for significant heat transfer from the tanks to the air in the room.