In the hot side of the cage where as in height should you measure the temperature. I was planning on using a thermostat so where exactly should I be putting the probe. I figured that since snakes are nocturnal they obviousely aren't climbing around during the day and chances are they are just sleeping on the substrate so I figured putting the probe just above the substrate on the hot side. If thats true what temp should the substrate be on the hot side. Im a little lost because I read the Ball Python Manual from kingsnake and it says BP's should have a 90 degree basking spot. I didn't think they bask being nocturnal. As far as heating what should I use for a 20 gallon tank?