Thermostat setting VE (RBI) rack

Hi all,

I have my VE-6 rack up and humming from reptile basics with a herpstat 1 attached. I'm having trouble getting accurate readings of the hotspot inside the tubs because as soon as I open it and move it to measure it via infrared temp gun, the temp drops! I was curious what you all have yours set to in order to get a consistent 89-90 degrees in the tubs (on the hot spot). Right now, the tape is exactly 93 degrees, but the few readings I've gotten inside the tub were significantly lower (low to mid 80s).

Thanks and cheers,
Gabriel