Ok a little update. I originally had the squirrel cage exhaust blower set to always on and the intake drawing from outdoors set to a thermostat that kicked it on when the temp inside the cabinet went above a certain temp. Once that temp was achieved it kicked it off. This was great except the "always on" exhaust was drawing in cold air at night through the (off) intake fan. This was freezing the plant at night when the lights were off.
So then I tried hooking both of the fans up to the thermostat. Due to the waterfarm, this made the humidity spike WAY up between fan temp cycles, the air became stagnant and created a continual hot layer at the top of the plant crisping some leaves.
So I think I've hit a compromise. The top exhaust fan is hooked up to the light plug so it's always on during light cycles and the bottom still works off the thermostat. No more stagnant, hot and humid air.
Here are a couple update pics. I've thinned it quite a bit. There's quite a bit of airflow from the 485 cfm exhaust blower but wonder if I should trim it some more.
Day 21