T8 temp issues

[SKO]

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I'm using a hand held heat probe, taking readings all over the tank. IS it possible that the Hobby Stat can be that far off? I have the probe sitting on the substrata against the wall on the cool side. The RHP is an 80 watt.

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It can be a bad thermostat too, but start by putting the probe on the hot side, dry that mulch out, and see what happens