Apologies in advance for the long post .Ok so I have now got 3 successful cfl grows under my belt. I have been running a cfl 600w actual watts not equiv. grow box with great success. I grow 4 plants at a time and have gone from 2oz a plant to now 2.5-3 oz a plant. But the buds just dont compare to hid lights growing same seeds. so now that I know a bit about growing I am wanting to step up to a 400w hps/mh grow tent setup. I want to still grow 4 plants at a time but only have 70 inches of height in my basement room where tent will be setup. I was looking at a 32x32x63 grow tent with 400w apollo digi. ballast, and venting with 6 inch carbon filter and inline fan. gonna be venting into my existing duct work for chimney which terminates to open air through roof. Now my question is with the setup i have in mind is it doable. and how should i be venting the grow tent? im used to passive air with pc fans at top of box and cutout in bottom but i know that aint working here. PLZ HELP ASAP sorry for the long read.