I feel I'm off to a good start with this process, thanks to many of you and the help. I have a 2x4x7 tent, 400 watt HPS/Mh air-cooled hood that will have ducting. According to my figures this area is 56 cubic feet. So what might be the standard cfm's for an inline fan to pump the good stuff in. 56 or a higher rating. Same with exhaust. Don't know about a carbon filtet yet. Will most likely will want the exhuast on hood or is there another better way. Thanks to all....