Being such a small tank it will struggle to keep the heat with this cold weather. I would use poly, old blankets, towels or old clothing (Anthing that will retain heat) around 3 sides of tank to lessen the heat loss if possible. Either that or replace with a 50watt heater. Seems like overkill on such a small tank and in warmer weather it would be but when room temp is around zero degrees over night and you're trying to keep the tank up to 24-28 degrees... That's me 2 cents anyway.