How about just putting some Styrofoam insulating board under the bottom tank glass and buying a good heating system with probably at least two 200 W heating elements and one separate thermostat. You normally need 2 Watts per gallon per 5 degrees. (The Innes book 19th Ed.). I was able to verify this equation recently when I put a 200W heater in a 20 gallon tank outside when it was 40 degsF out ( the water went up to 45 degsF). Steve Pituch ------------------ To unsubscribe from this list, please send mail to majordomo@thekrib.com with "Unsubscribe aga-member" in the body of the message. Archives of this list can be found at http://lists.thekrib.com/aga-member/