So just go ahead and stick the thermometer probe down under the substrate against the glass where the UTH is? The UTH was a basic one so it does not have a thermometer. I didn't see any that did while I was looking but I could certainly be wrong. I will also reduce the amount of substrate to make sure it is around 1/2 inch thick. Also I worry about the temp at the top of the tank where the bulbs are. If he were to climb up there I wouldn't want him getting scorched. Any particular thermometers recommended for those types of readings?
I originally was going to have the red bulb for day as it's a little warmer and black for night as it's not producing the same heat as the red. This was just per the suggestion of the breeder that I lower the temps slightly at night.