one thing that really helped me on this design was using plexi glass in between the bulbs and plants. I hadf the plexiglass cut at Lowes to where it was completely flush with the rubber maid except for one end which had an inch or two gap. On the end opposite from the gap I had an exhaust fan pulling the air over the bulbs and out of the box. I had 12 23 watters in there and the temp stayed aroud 75 with the exhaust being 100.