Quote Originally Posted by Gundy
My cold is in check, reading a constant 81.

I was just worried thinking why the temperature is reading so differently directly on top of the substrate.
I dunno....I'd have to see the setup myself to have a decent guess as to what's going on. It's possible the layer of substrate is thicker than you think it is....or just not conducting the heat very well, regardless. Or, if the ambient temps in the room are really chilly, and the tank is glass (does not hold heat well) the warmth from the UTH may be dissipating too quickly to maintain a warmer temp at the surface. But....that's just imaginative speculation on my part.