Does the UTH have a thermostat? The dial thermometers do not work, all they do is tell you what the temperature of the glass is. Get one of these, they cost $12 at Walmart.



Probe goes on the hot side over the UTH, and the unit sits on the cool side. It measures both temperatures and humidity.

It sounds like the UTH is too hot (needs a thermostat) and dropping the temperature at night isn't good either. Does your enclosure have a thermal gradient?