Carbon filter on Intake side of inline fan

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.