Your basic uth should run around 110-120 degrees with nothing controling it.
I don't use them anymore due to my snakes being in a rack, but when I did I found it easier to leave the backing on the uth and just lay it under the tank. This way you get less heat and don't have to peel it off when you upgrade tank size.
If you do take the backing off I apply aluminum foil tape to the sticky side.
And for those that asked. Foil tape is at any hardware store used for furnace duct work.
Gavin