To update, I just got a exo terra heat pad 8"x8" to heat up a 20g glass tank. That was the only size they had, I also got a rheostat. This is all for my brother until he gets the money to buy some good stuff. So, my questions are: 1. How long does it take for UTH's to heat up? 2. Are you supposed to stick it directly on the cage, or should it heat the cage just fine from below? I dont want to stick it directly on the bottom of the cage because it makes it a pain to clean, so it's sitting about two inches below the cage. I've been watching it for the past hour and the temp is not rising!!