I sit my carbon filter on the floor and put my inline fan directly on top of it. I did this when I started growing 8 years ago and they fit fine. Now I have different models and some fit and some don't of the same model, it makes no sense. My question is can I use the 8 year old carbon filters still? Like can they go bad or back up with stuff in them that they sucked in like micro particles? The air pressure coming out of the ducting is very good pressure so they ain't clogged or anything. I don't care about smell at all.