No waterbed heaters they are bad creat hot spots. In my 750 I had about 1800 watts of heaters in the sump and during the winter in my basement the pond would stay right about 77 now mind you there was 2" of styrfoam insulation under the pond and the top was covered at all times unless I was feeding or watching the air temo iin my basement was around 60 so according to the "experts" i didnt have enough wattage of heaters but it worked for me go figure.. and hey phil long time no speak we still need to take time to have our coral propogation talk
