Continuing to dial in temperatures: I've added a second 4" in-line duct fan which helps to pull air from veg into bloom. The existing 4" fan is now connected to a first round prototype for a cool-ish-tube setup. It proves that it will work, but I need to redo it with a better glass tube. The only thing I could find was a $2.75 candle holder with a glass tube which just barely suffices for the moment. It is far too narrow, creating a massive constriction and far too close to the bulb. It is also just barely too short so the very tip of the bulb is actually covered by the 4" dryer vent. The light space is currently partially divided from the bloom space by a sheet of plexi-glass which conveniently manages to cover about 75% of the cabinet space.... just enough to divide the nice warmishness below from the desert sun above. Both the plexiglass and the horrible cool-ish-tube rendition make a huge difference.

This rig, with the help of the winter chill, is able to keep the bloom chamber's temperature no more than 4 to 6 degrees Fahrenheit above the veg chamber's temperature (score!). Temperatures are still higher than I'd like them to be overall. It's now 60F in the hallway, 75F in veg, and 80 in bloom. This is with my plastic curtains closed but the blanket which covers my space tied back. Closing the blanket over the rig as well raises the temperature of both Veg and Bloom by 5 degrees.

It looks like with a bit of work and part scrounging, I should have ventilation under control here shortly. This grow space is coming along a bit like a cross between Red Green (duct-tape combined with bits from things your neighbors threw out can solve all of the world's problems) and Tooltime (Arr Arr Arrrrrr Ugh More Power!)