question about temp

i was recently told that i should be taken the temp in the cage on the glass and not on top of the substrate... on the glass the temp is 125ish but on the substrate its a little under 90 ... should i use a thermostat or leave it alone. Im afraid the temps will get to low on the substrate if i use the thermostat.

how deep is your substrate?

30 degrees is a pretty big difference.

You really do need a thermostat to control that UTH. Your snake could push the substrate out of the way and lay directly on the glass above the UTH and get severely burned.

This is very true. My normal male pushed all his substrate away and laid on the glass over his UTH and burned himself pretty badly. The section of his belly was very red and 3 large blisters formed, I blamed myself I vowed to not let it happen again. I found an idea online and went to Wal-Mart and bought a extension cord and dimmer switch. If you cut the extension cord and wire the dimmer switch in the middle, plug the UTH into the extension cord you have yourself an easy way to control the temp of your UTH.

There are dimmer switches that you can just plug the UTH into. They are called piggy back dimmers and can be found at home depot or lowes.

I would suggest getting a thermostat instead of a rheostat. Rheostats require constant adjusting and can still spike the temperatures.

id say its maybe an inch and a half to 2 inches deep ... i dont remember the exact name of the substrate but its similar to reptibark.

Personally I'd use a proportional thermostat like a Herpstat or Helix. You set the temperature you want place the probe and done. No fuss, NO mistakes. My ball often pushes the substrate around and if it gets thicker or thinner the temps go wrong. Dimmers are ok but don't account for variable room temps if the temps increase in the room the dimmer needs to be shifted. I personally have quite a variation this time of year as the weather gets colder and warmer and the heat is low or off.