Ok so a little information first, I'm going to be growing in a closet with a 3x4x6 framed box using a 400w MH for vegging and a 430w HPS for flowering. I've been looking into inline fans as well as carbon filters and trying to weigh my options, and figured this forum would be a great place to ask. Option (A) Is that I go with a 175cfm inline($150) and a 175cfm max carbon filter($100) total equalling $250. Option (B ) Now heres where my temptation begins, for only $50 more on a fan ($200) I can get one rated at 420cfm, both of these are from the same company btw. However a store bought carbon filter rated to withstand these speeds costs around $250 where I live equalling $450. Now I've seen a lot of good looking DIY carbon filters on this website however most of the people using them are running "slower inlines" (around 175cfm and under). So finally I come to my question, should the 175cfm fan/filter combo for $250 be adequate ventilation even with the heat of a MH in such a small room? Or is it possible to make a DIY carbon filter from home capable of successfully masking the scent of a flowering plant with a 420cfm inline? One of the reasons the 420cfm fan is so tempting is I would like the ability to possibly vent a flower and vegging room down the road. However $450 for a fan/filter is just too much for me. I essentially have the rest of my grow planned out apart from this, and would love to hear from people who have experience before making the final decision, thanks.