I need to have my fans on the bottom of the unit. I was trying to think of a way to vent hot air from above to down below out the air vent. I was thinking of a cool tube type design. If I can isolate my heat (light) from the grow chamber, I can cut down heat by ALOT. I was thinking I would use tubing and such to create a passage for the air to flow through. I don't know if I want a passive intake since I need it to be lightproof, so I think I might run a very quiet 80mm fan as an intake then have the 120mm exhaust fan be connected to the cool tube type setup via pipes. I would leave some room around the cool tube open for an intake for the exhaust. So that is my plan. Got any suggestions?

Like the picture except with a 80mm intake fan on the bottom.