I just set my flex and t-stat up a couple hours ago. I went with the Ranco probe taped to the bottom of the glass then the flex-watt and on top of that i insulated it with a piece of reflectix. My current temp above the substrate surface on the hot side is 85.8. The Ranco is set high at 120! I have about 1 inch of Cypress mulch. The t-stat keeps shutting on and off but I have it set for a 3 degree diff. so it's reaching 120 but not inside the viv. Should I just wait and see what happens overnight and let the temps settle? BTW cool side is currently 75. I have my overhead black light bulb over the cool side but it's plugged into the powerstrip with the t-stat and keeps shutting down when temp is reached on the flex on the hot side. Is 120 wicked high??