where do your lizards spend most of the time? If they are arobrial, thus having a couple branches for them to live on (like you would for a green tree python or amazon tree boa), then you want it on the highest perch.
If it's a typical lizard that's going to be on the ground quite a bit, it depends on the type of thermostat you have. If it is one that you just twist the dial, put it right on the substrate and get a thermometer and adjust it accordingly. If it's one that tells you the temp, you want to suspend it about an inch above the substrate, unless you want to get a second thermometer
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-Chris
The reason mainstream thought is thought of as a stream is because it's so shallow. -George Carlin
A fool doesn't learn. A smart man learns from his mistakes. A wise man learns from the mistakes of others. Which one are you?
My Website
N. American Rat/Corn snake care sheet I wrote
Information on substrates
Current snakes:
0.1 Licorice Stick Black Rat (Lola)
1.0 Black Rat (Frankie)
0.1 Texas Bairdi (Rosa)
0.1 Blue Beauty (Brunhilde)
1.0 Green Tree Python (Monty)