I'm building my grow room, the area is gonna be 4'wX4'dX8'H. I have a 4" carbon filter rater for 150-265 CFM and a 4" fan rated at 170 CFM. IA 400w HPS with a bat wing style reflector. There will be a few bends in the duct work... I think 3-4 90 degree bends to get outside, less than 15'.
I'm...