I have 2 (off-brand) 26 qt. tubs (approx. 6.5"H x 15.5"W x 23"L). I didn't have time to order flexwatt and wait for it to be shipped so I went to the local pet store and picked up 2 Zoo-Med UTH's (30/40G). The are both foil-taped to one side of each tub, with the backing paper still on. The probe for the herpstat is taped to the underside of the UTH on one of the tubs. I have the temp set to 97 to be able to get the plastic above the center of the UTH to right at 92+/-.5... I'm fine with this, I guess the plastic and UTH backing paper are absorbing around 5 degrees. The problem is with the second tub. The temp keeps fluctuating and last night it was only reading 86.5 on the hot spot... Any ideas on what could be causing this? Only one I have is that when I take out the non-probe tub, the open air cools it, but since the probe is still reading the same on the other UTH no additional power is supplied to maintain the temp...
Maybe if I taped the pads directly to the rack instead of the tubs.....