Thanks for the advice, friends!

I'm concerned about adding holes because the bin already has two rows of holes drilled along both of the long sides, and the temp is on the low side of good already even with his UTH thermostat turned up pretty high.

He's in either a cypress mulch or coconut; I don't have enough experience to tell by looking, but it's lot of large dark brown chunks of wood. And yes, it is holding moisture like crazy; you can see the water beaded up under it through the sides of the bin. Outside the bin the humidity is somewhere around 30-40%, but inside the percentage fluctuates anywhere in the 90s. What would you guys suggest as a humidity-lowering substrate? Or should I just replace the soaked stuff with new substrate? I bought a bag of coconut husk a few days ago.

I would guess that his water bowl is probably an 8" diameter; I'm not home to check right now.

Thanks again!! And Mobius thanks you too.