Cheers JackdaWack for actually understanding my point. I'm not 'trying to make it harder than it actually is' though i would simply like to keep my grow room seperate fom all my ducting, if this setup isn't posible then someone should invent an inline passive carbon filter IMO.

So are you saying that the upper section should have a simple hole where the air passes through and into the filter like the diagram attached?

Cheers

TB