Quote Originally Posted by Rikoku View Post
First time I run into someone mentioning this, In this case would you want the monitor the ambient temperature or would you still be concerned with substrate surface temp?
You dont run into this often because most people still love to hold on to their cherished UTHs. There are two ways of doing this. If you are still concerned about maintaining a gradient, then you would be taking temp measurements on top of the substrate. If you are like me, and disregard gradients, then you would take the temperature of the ambient air at snake height.

You must keep in mind though that using ambient heat only requires a well insulated enclosure that holds heat exceptionally well, or the use of multiple heating elements to maintain uniform temps.