Can I attached a carbon filter at both ends of my ...

There is no point to putting a filter on the inlet side of your fan, it does nothing. Replace the carbon in your existing filter as a first step.

Dual carbon filters will burn that fan out faster then one. If smells are seeping though the filter you may need to replace it with a better one. Filter do not operate well in high RH, smells seep though them and once the RH is lowered again it will begin performing more optimally. They say you can re-prime carbon filter by baking the carbon filler in them aorund 450f for a few hours then letting them cool but all the volatile gasses and smells they absorbed will be released and will stink up the place real bad. Best to mix it into your compost or garden bed then fill it up with new carbon if you can or just buy a new one. one every 2 years for constant growing is about ave. depends on the room size and how many plants in conjunction with CFM. Good Luck!

Throw a dryer sheet a day over your discharge vent it will mask any extra smell from putrid bud for the last two weeks

Another fake account from HerbalEdu... miserable

Yes you can. But your exhaust fan may be not as efficient as without. You can also use ONA gel or block, it works perfectly fine to neutralize smells in a room. I hope this helps. Good luck 🍀

it's preferable to have the the carbon filter fixed to the extractor intake, but yep it also work if fixed to the extractor output. Mine is fixed after the output. Happy growing