Calibrating temperature probe RKE

[WarDog]

Where are you running the probe? In the sump closer to the heater? There will naturally be some temperature difference, however 4 degrees seems pretty steep. I wouldn't be too concerned with running a temp of 78, it's really the amount of fluctuation within a day that you want to avoid. 76 is on the low end, with 82 - 84 being on the high. I wouldn't panic until around 85.

Here's a temperature poll.