The $20 thermostats are not good for heat tape because they are on/off type thermostats. Its recommended that you use a pulse type thermostat for heat tape ($75 ), but i just use a plug-in type dimmer aka rheostat. I just watch the temps with a temp gun/digital thermometer and adjust every few days. I have a dimmer for every 3 shelves. Hope this helps, best of luck.
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-Sal
3.8 Total Leopard Geckos (Listed below)
1.0 Hypo Golden Jungle
1.0 Super Hypo Carrot Tail Baldy
0.2 High Yellows
0.1 Normal
0.1 Patternless
1.0 Patternless het Rainwater Albino
0.3 Rainwater Albino het Patternless
0.1 Patternless Albino (Rainwater)
2 Eggs currently incubating!
1.0 Ball Python