save yourself a buck go with 1/2hp chiller(http://www.selectaquariumsupply.com/servlet/the-29/tradewind,-chiller,-aquarium,-supply,/Detail 1/4 hp per 1000w is fine. If you dont believe get a 3/4 hp dont get 1 hp you just wasting money unless you wanna expand. You can get this foam insulation...