Then consider yourself lucky. i had the same experience as hemp but it was almost 2 years ago now. I had one for a 6" fan. forget the cfm rating but it was what they recommended and holy fuck my driveway stunk like a skunk the first day I got home after using that thing. I went with plantlightinghydroponics set up with the valuline fan and it was WAY better.Listen, not to be an asshole, but WRONG! I had a dispute with people over there regarding a discount I felt I deserved but I do use their carbon filter along with one of their imitation can-fans which is like a third the price of an actual can fan on a bad day, and I have 8 AK-48, notoriously stanky, that I can hardly even smell when I'm in the room-- and that's with the fan barely on, like set so low on the fan-speed control that it is just barely pulling air from the filter. I just 100% disagree, perhaps you had a bad experience but I am having a very good one.
Well actually it just worked and that made it way better lol.