I would like to heat my 100 gal bait tank that I keep in an unheated garage. My goal would be to stabilize the temperature at 50F to 55F. I would not have to worry about freezing and the bait would be close to the water in the East Tennessee lakes. Aquarium heaters are not designed to allow them to drop below 65F. Pond deicers and stock tank heaters are designed to prevent freezing but not for maintaining a set temperature. Anny ideas?