I have two separate 8" fans pushing cooling air (from the next room in the case of one, and from outside in the case of the other) through 3 lights each. The straight pipe goes directly outside, as does the cooling air from the lights. I may have to put a carbon filter in the room once flowering starts in earnest. At least 12 of my girls are ready to go to 12/12, and possibly all 18. I have some final light-tightness issues to deal with this weekend, since I do in fact dread hermies. Come summer I may have some heat issues, even with the air-cooled lights. To help with that, I think my photo-period is going to be 10pm-10am. I'm hoping to end up with a continuous harvest set-up with approx. 80 plants in flower at any given time. Please feel free to comment as I'm always looking to learn more, noob that I am.