Ok i just picked up a vortex 600 6" fan 449 cfm and also a Profilter 75 carbon filter. Damn these carbon filters are heavy!!! Also got a speed control unit for the fan also.... Im a little confused here... I would like to vent the box`s and run ducting to cooltube to carbon filter then out through roof. The Profilter 75 is a reversible filter it has a flange on one end that will fit to a 6" ducting the other end of the Profilter 75 is a solid plug that can be taken out for when the use of the one end is done and you turn the canister around and use the other half of filter.... My confusion is that if the canister is sealed on the one end and open on the other how do i hook this canister up so that all my exhaust filters through the canister then out through roof? Im confused can anyone shed some light on my dilema????? Thanks