I have seen a few threads on this subject but I am hoping to get some good feedback b4 I make my next big purchace. not sure what fan is better but here are some good deals for ya on inlines Tjernlund Retail Store-High Performance Metal Inline Duct Fans (Models M-4, M-6, M-8) has 6" inlines w/530 cfm and says they will price match on similar fans with 1 year warrantee this is a 6" hydrofarm active air inline for 79.00 with a 5 year warrantee: 400cfm http://www.plantlightinghydroponics....an-p-2754.html and then there is the valueline inline fan with 432 cfm for 79.90 http://www.plantlightinghydroponics....an-p-2260.html I am gonna need three inline fans but I am not sure which ones to get. I would hate to buy three fans that I dont like, I almost wanna buy one of each but that is just inconvenient i think. I will use one to circulate my veg room with passive intake(anyone with any info on passive intake could help me greatly) one for flower room for air exchange w/ passive intake and one to cool my hood. any suggestions on which one or if i should mix it up with different ones. I will use a carbon filter so I was leaning towards the valueline or the first one because of the cfm... my rooms are both 4x4 so it may be a bit overkill to have 500cfm but then again its never too much circulation right? Also I have been reading and I have gathered that I dont need fans for intake that Passive intake will work? Not sure about venting too much so input would be used and greatly appreciated. opionions/experiences/reviews would be helpful. Gotta make a purchace soon so I would like some input in helping me decide. Thanks Guys!!!