there's a few reasons why placing the 'stat probe between the heat pad and bottom of the tank is common practice:
• this ensures the probe cannot be messed with/moved/urinated/defecated on and give a false temp to the 'stat, this increasing or decreasing the output. it should always remain the same.
• snakes can and will burrow down to the bottom of the tank. you say you have 4' of substrate: that's a lot of mass for the heat to pass through to get to the probe. what is the temperature at the actual bottom of the tank? i'm sure it is much hotter than 90°, which is probably why the snake avoids the warm side.
Reply With Quote