What type of filters are you going to use? Big canisters like FX5s are about 50 to 60 watts I think but the filter on my 750 has 2 pumps a mag 24 which i believe was about 150-165 watts and a supreme hydrive 4800 which was a little more so theres 300+ watts running continuously. So if Youre worried about electric Id do a big canister and keep your house warm so the heaters don't run a lot. And put lights on a timer to run only when you are mostly around the tank