Heating Tank Problem

[Hill111]

The first picture is from the other day when I took him out of the substrate and put him in the pedialyte bath, it's a before and after pic. The second one is him today buried in the substrate again, and the third is the tank. I have him in a pretty low traffic area so I figured I didn't need to cover the sides of the tank, but I'll pick that up today too and give it a try!