help/ UTH size?

[Toddnkaya]

Is a 6 inch by 8 inch UTH too small for a 20 gallon tank?
Also where do I put the probe for the acurite? In the tank or under the tank?
Thanks!

[Stewart_Reptiles]

Personally I would go with at least 6 X 11 as a minimum since glass tanks are not the most heat efficient.

Thermostat probe should be placed directly on the heat source.

Thermometer probe should be placed should be place in the enclosure right above the heat source.