Ideally you would have a carbon filter attached to a fan that would suck air through the filter and back into the room, therefore continuously scrubbing the air. A separate extraction fan would then take care of the ventilation. However, oftentimes monetary factors prevent people from buying two fans.

Depending on the size of your grow there could be traces of smell left in the air if it is only scrubbed once, and then evacuated. The best way to to employ the system I described above: two fans, one w/ scrubber, and one for extraction.
Perp Reviewed by Perp on . Ventilation Question I was wondering how a ventilation system with a carbon filter works? Does the exhaust air go through the carbon filter then outside? If so, wouldn't there be traces of odour since the filter can't get rid of all the smells? Which is the best venting system I should use to make sure there are no smell leaks? Rating: 5