Quote Originally Posted by soapdog View Post
In my sterilite tub I have a small heating pad on the hot side regulated by a thermostat. The thermostat probe is on the bottom of the mat and reads a bit hotter than the actual inside of the tub, so it is set to 95 degrees. Inside the actual tub, under the substrate, the tub reaches 90 degrees. On top of the bedding on the hot side it only goes a few degrees higher than the ambient though (maxing at maybe 85).

Ambient is around 80 degrees. Room temperature is in the 70s, but this was achieved by using reptile heat cable along the back and one side of the enclosure, unregulated by a thermostat, but the walls don't reach a temperature hot enough to burn my snake.
So your hotspot is 90? That's fine.

If the tub is 90 and the aspen is 85, he'll burrow if he wants to get warmer.