I have one of those UTH (Zoo-Med) stick on types and, was wondering if you absolutely have to stick it to the viv. ( I'm using Sterlite for that.) I heard that you can sandwich them between two tiles instead. Has anyone done this and will it work? Also, what kind of tiles do you use? I heard you can get them at Lowes/Home Depot. Just in case you're wondering...I will be using a thermostat too. I may want to change to Flex Watt in the near future and would rather not stick the one I have on, if I do not have to.