I use a Hydrofarm thermostat, which is not too expensive and works well. You want to put the probe between your tape and the bottom of the enclosure, then use a thermometer to track the actual temperature inside the enclosure so you can adjust the thermostat accordingly. My thermostat is set to 94 to maintain a hot spot of 90ish. Accurite thermometers are inexpensive and have a probe so you can track both the hot and cold side temps.

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