Carbon filter on Intake side of inline fan

Agree with Numbers, Neg Pressure is key... eg always sucking air into the tent, this way the smells can not come out of the tent. Putting the filter on the intake or the exhaust does not matter, it will function the same. At least mine does. However I don't like a lot of extra outside my tent so its inside on the intake of the fan. If you are venting outdoor. Don't use a filter unless you have too. It lowers the effectiveness of the fan by about 1/2, filters add a lot of drag and resistance. That in turn can lower the life of the fan. I like to get an over sized filter so the CFM is not affected to much and i make sure my fan and handle the rate of the filter.

Negative pressure is the key to smell containment... probably better with it inside the tent, but as long as no leakes leading to the filter outside the tent, it will also be effective. but, like i said, those filters are drictional. Some are reversible but not all. if you can't remove the tapered end and flip to other side, probably not reversible.

Some are reversible. You really shouldn't have carbon getting into the fan, maybe that one is set up for reverse flow? When air goes the wrong way through it you can get some loose active carbon, but it really shouldn't happen the other direction unless there's something wrong.

Most people have to use it on the intake as they're removing air outside.