Which thermometer do I trust...

[SwiftStorm]

I have a little problem. My apex shows the temp at 78.1, Brs controller at 77.3, and 2 cheap digital therms reading 76.1 and 75.0 (in tank). I guess I don't have a problem since the temp is usually consistent. But which typically is more accurate? 3 probes are in the sump with 1 in display.

Thanks

 

[Quietman]

No way to tell really...the Apex is a bit better design but you still have to calibrate it to something. There are calibration thermometers out there...not exactly cheap but not too bad ($60-100). But more than I need to spend on 2F difference. I use the Inkbird and Milwaukee pH pen (has temp too) average the difference for my Apex calibration. That said, Apex was <1C off so high confidence.