Rack temp question

I just set up a 16 qt rack and have a question about the temp. I have a Herpstat 1 set at 95 F and a backup Ranco set at 100 F. Is it better to use the digital thermometer in the probe which is measuring air temp or use the surface temp reading using a INfrared thermometer? My air temp is 87 and my surface temp on the hot side if the tub is 89 F.

Thanks

Both the probed thermoneter and temp gun have a certain amount of error in their readings. For most it is +/- 2 degrees F. This means that when using 2 devices they can read 4 degrees apart and still both be working. For them to be that close is a good thing. I usually split the difference and go with that so in this case I would say that your temp is 88 degrees. I would set the Herpstat 1.5 degrees higher to see if you can get the hotspot up to 90