Ok guys so i have a 7 level rack system that i builded myself, lately i been getting more snakes and today i got a adult Pastel Lesser enchi ball python. i prepared his new tub in the 4th level of my rack and everything and when i checked his hotspot temps, my temp gun was reading 83 and in my top level was at 91 why do i have 7 degree difference and how do i get my 4 level to be at 90 degrees ???
i dont want to increase my herpstat temps cus if i do it my 4th level will be at 90 but obviously my firsts levels will be more than 90 cus of the temp difference im having
PLEASE HELP ME I DONT KNOW WHAT TO DO ANY ADVICE WILL BE HIGHLY APPRECIATED
I DONT WANT TO KEEP MY NEW SNAKES WITHOUT THEIR PROPER HOTSPOT TEMPS

FYI: im using a 4" THG Heattape and a Herpstat 2 which i have at 96 to hit a 90 degrees

sorry for the long story
and thanks