Temp help

So I just built my new rack out of an old desk and i am having trouble with the temps I was wondering if yall might have some suggestions. I am using Flex watt heat tape, and its running off a ranco. My temps on the first row of the rack are perfect 86, the middle row is 90 and the bottom sits around 84. I was wondering if there is any tricks to make them a little more consistent. The heat tape is 1 continuous strip snake'd from top to bottom. I have the thermostat running at 87-88. If there are any tips yall have or any more information needed please let me know thank you very much.

P.S. this is just the testing phase of the rack so there are no animals/water/bedding just empty bins.

are these temps inside the tubs?

Yes inside the tub, where the "hotspot" would be

i would probably add a second strip of 3" flexwatt to the first and bottom row and adjust the thermostat down 2 degrees and you should be sitting around 88 on all 3 levels. It may take a little tweeking as far as probe placement.

Im having the same kind of problem with mine. my top shelf is 88 the second one is 87 and the third one is 90 for some reason and i have the thermostat at 88. cant really figure out how to even it out either

I would just bump up the thermostat to 90 then the rack should be in a safe range which is 88-94 degrees! Within that range, you should have no problems! My rack varies a little on each shelf!