i have a small UTH that i have placed on the bottom left side of my 10 gal. i was a little concerned about the possible stress fractures to the tank, but aesthetically, i just couldn't bring myself to stick it on the side. i keep the water bowl on the opposite side and that seems to be working out well as my toads can chose to stay in their hidey spots on the warmer side, or meander on over to the cooler side for soaking. i unplug the pad a couple hours before cleaning the substrate to allow it time to cool off so i'm not as worried about the drastic temps causing the glass to crack. and actually, i think i have a small enough pad that it doesn't generate a ton of heat, so i'm not even really worried about my toads getting too hot if they are right on top of it. i have noticed it definitely does keep the substrate on the dryer side, so misting daily is a must....but that helps me keep my humidity at better levels as well. so theres my two cents worth!