thanks everyone, now how about where do i place the probe? I have flexwat tape going down the backside of the rack(back heat i think you call it). Do i want to tape it right to the flexwatt or do i just put it between the tape and tub? Sorry for the silly questions but like almost every ball keeper i started out with tanks and became overrun by tanks anyway its better for the snakes from what i hear. i have 4 at the moment however i have 8 emtey tubs and the white plains reptile show is in one week(YES). I guess im hooked