Thanks for your input crazywill. There actually is a passive carbon vent that is approx 6" at the top of the cabinet. We were going to put venting from the wall to about the middle of the cabinet since we still have to move around the shelf as the plants grow. We will use a 80cfm in line duct fan to pump fresh air in, and the hot air will just escape out the top! I will keep you guys posted on how well this T5 does from clone to flower with bloom bulbs. The world of T5 lighting is new to me and that is what I mainly wanted to see about.