Differential is set at 1. Everything on the thermostat is set how it should be.

My tubs are also in a room with pretty steady temps. Anywhere from 76 to 80 degrees.

I hate worrying about stuff like this. I just want everything perfect. Would it be better to tape the probe to the flexwatt underneath the tub? Or leave it on the bottom of the tub right above the flexwatt.

I figured I'd get more stable temps that way. My helix's are set up that way and they're fabulous.