You mentioned that you have a fan to pull air from upper to the lower. Is that recycled air? I think that fan may be unnecessary. If you have exhaust on top, and intake on the bottom of both chambers, then you should not need to recycle that air. It may work best for you to remove that fan and try to get the air from both the lower and upper chambers circulating towards the very top of the total cabinet, where it can be exhausted.
d00g Reviewed by d00g on . Chasin temps....Aaaaauuuuugh! This is driving me nuts!! Garage cabinet grow....6' wide, 2' deep and 8' tall split in half across the middle. Veg on top, flower below. Air exchange between the two level's and I just "rolled" the flowering lights so they are on 7PM to 7AM to help with heat at night. Upper is 7AM to 1 AM, so there is an "overlap" when ALL the lights are on. I had to add a radiant heater below for heat before I "rolled" the flower lights 12 hours to a 7PM start so I could use the heat being generated. So Rating: 5