I use a UTH on the warm side and a 50W red bulb on the cool side to keep the ambient temp up....otherwise the ambient temp drops below 75 degrees.....my thermostat is connected to the UTH and I have a rheostat connected to the red light so that I can adjust the ambient temp depending on the temp of the room. It seems to be working very well. I have covered 2/3 of the screen with foil and left an opening near the light for ventilation.....I'm concerned about the ventilation in the tank, if you cover the entire screen except for the opening where the light goes.....anyone else wonder about this???Or is it just meworrying for nothing??