For larger tanks, working on getting an 8 foot 180 setup, is it best to have one large wattage heater or multiple mid-wattage heaters? With the multiple heaters would they work against each other in heating or as long as the water circulation is good there shouldn't be an issue? I was debating placing two 200 watt heaters next to the outtake of both of my canister filters so that in my mind at least it should warm the water in the tank throughout. Tank is in my basement so in the winter time it gets somewhat cold down there. Summer time should not be an issue at all.