Thanks you very much! I kind of just figured that's all it would be but was unsure about the size of the uth, it just looks so small compared to the 20gal. My ambient room temp. stays around a constant 70-72 year round for the most part. So if I get this right you're saying get the warm side up to a temp no hotter then 95 with just the uth and see how warm the cool side gets from doing this. If it gets warm enough on the cool side, then I shouldn't need the che? Did I get that right? I just cant see that little uth getting the cool side up to the low 80 at the far side of the tank, it just seems too small. Would there be anything wrong with getting a larger uth? That way if it's needed, I have it and if not, the thermostat can control it? Thank you again for all the info