Ok I built a rack, stabilized 3 out of 5 habitats so far...now my issue. I have my thermostat probe sitting on the FW on the middle shelf, set at 96 to make it about 94 inside the tubs. First, 4/5 would be at 96 with the bottom FW reading 108. I put all the tubs in the rack, this stabilized the temps, but now the top and bottom FW are reading 84.4 while the 3 middle shelves are 96. What's going on?