Okay maybe I didnt make it clear. The probe is directly on the heat tape and its in the middle of the rack system. Today I checked the temperature with a probe thermometer and a temp gun and each read the ambient temperature exactly give or take .5-1 degree. When I put the thermometer probe on the heat tape, it read the same thing as the on and off thermostat give or take 1 degree. BUT when I put the thermometer probe on the inside of the tub and taped it down onto the tub where the heat tape is going to be at, the reading for my thermometer probe is 85-87 while my temp gun reads 91-100. And the funny thing is that the lower tubs, the higher the temperature. I know that 10 watt 3 inch heat tape gives off more heat but I set my thermostat at 92. The tubs should have a hot spot of 91-100.