I have build a 6 foot tall snake rack with 11 tubs in a single vertical stack, using back heat. Since heat rises, my top tub in the rack is at 91 degrees and the bottom tub is almost the temperature of the room about 78. These readings were at the back of the tub at the closest point to the heat tape. I have installed insulation board in the sides of the rack to hopefully keep the heat in. I have tested this for about 12 hours and there doesn't seem to be much of a change. The rack has a 2x4 rectangle base that is hollow. I put in 2 layers of insulation board there also. I have only been testing this for a few hours, but as of now not much has changed.

How would you recommend getting a more even temperature throughout the rack. I know there will be a temperature difference between the very top and very bottom, but not by this much. I have extra heat pads that I could run to the cold shelves but at $22 bucks a pop its not very appealing.

Another option I'm seeing is getting more heat tape, and then just using belly heat through the whole rack. Since there is only one temperature probe, without buying another thermostat, I'd have to remove the heat tape from the back to do this.

I would much prefer to continue using back heat since I measured the distances between the tubs so close that even a layer of heat tape and foil tape would cause me to have to raise all of the shelves up. This could be done, but I am hoping there is a way to do this without having to change everything.

For example since heat rises, do you think that drilling a few holes in the top of the rack would help? This would lower the temperatures in the top few racks by letting the warm air escape. Then by raising the thermostat more, the I would raise the temps in the lower cages without increasing the temps in the top. This is just a thought.

I just posted a different question a few days ago and was greatly impressed with the quick responses. Hopefully yall can help me again.

Thank you,

Colby