Well, I finally ordered a ranco thermostat (YAY) I got tired of the zoo med 500 r constantly cracking out and now I think its finally failing.

So heres one question. I have a steel shelving thing with 3 20 gallon long cages on it stacked one above the other. With the Ranco which cage should I place the probe in? All cages are the same size, same uth's and will require the same temps. I was thinking the middle cage.

Also, I have the repti therm uth's, I HATE them. They are two small for the cage, I bought the 20 gallon ones. They work but I find them too small. I have been looking into the cobra heat mats, how are they? For 20 gallon long cages should I go for the 11 x11 size seeing as how the cages are 30 x 12 inches?
I have also considered buying flexwatt but want to wait until my husband gets cages built.
Thanks
Kristy