Can't get susbtrate temp up?

[Sonya610]

I'm planning on cutting a sheet of acrylic to cover it tonight, so I'll see if it has any effect.

I'll roll the reptibark back to an inch or so as well. Will removing the paper towel help?

I would leave the paper towel, it is too thin to absorb much heat and will make cleaning easier. Yeah I think the directions that come with the UTH talk about how thick the substrate can be, if it is too thick the heat just can't penetrate.