Yeah...as I re-read my post, I realized I forgot to mention different sized heat mats would cause an issue, too.![]()
As for the T-stats...there are four reliable brands. Johnson and Ranco are both on/off T-stats, which control the temps of the mats by flicking the power on and off as needed. Both are equally reliable, so far as I know. Herpstat and Helix control the temps by altering the amount of power flowing to the mats...they tend to keep more reliably steady temps...but also cost more. In the interest of saving money, either a Johnson or Ranco is fine, in my opinion. The degree of tolerance for the on/off switch can be set as low as 1 degree, so the temps don't vary a whole lot.