greenjeans
Hydroponic Heretic
Another thing you could do, would be to change it up like I said above, and then put the booster fan where you have the centrifugal fan now. The intake is really irrelevant IMO. passive should be fine. Putting the fan on the intake is only really going to help if the room is sealed well enough to create positive pressure. You want to create more suction, and make it easy for the fan to push through the long stretch.