heating glass tanks

[rwg]

Well, I switched substrates from "forest bed" which I think is some kind of mulch, to aspen shavings. Figured I may need to recalibrate my rheostat setting so I took some measurements. Admittedly, this was with a crappy thermometer, but here's what I found:

Setup: 40gallon short with snap-on wire lid, and large UTH directly under one end. 2-3 inches of aspen. Plastic aquarium frame leaves app 1/4 inch clearance between UTH and bottom glass surface. UTH is on a rheostat.:

ambient hot side: 75
ambient cold side: 72
ambient outside of tank: 70
ambient inside hot hide: 80
temp hot side under substrate: 110
Note: glass on hot side hot to the touch.

To get the "under subtrate reading, I put the thermometer on the glass on the hot side, and burried it under substrate to normal depth.

I have some thoughts. Either the aspen is so good an insulator that the glass is getting too hot, and the ambient temperature is almost unaffected by the heat source OR glass sucks in general, aspen or no aspen, and I wont get the ambient temperature I want in there using a UTH under a glass tank.

I'm going to turn off the UTH tonight (turned it way down already), and let the floor cool. Then I'm going to switch to a reflector lamp, and do all the same readings to see if a lamp is better for providing the right temps and gradients in a glass aquarium. I'll post my results tomorrow.

For the record, this is a corn snake enclosure.

rg