I've never understood why the manufactures and users of exhaust fans and filters are so hell bent and bound to do it wrong. Always set up your exhaust fan to blow into the carbon filter. Never,, ever suck through it. You put any filter or device on the suction side of the blower and you completely destroy the fans performance. All specs manufactures supply is of the exhaust fan unit with no filter attached to it at all. I was a manufactures rep for 20 years in the pump, blower, chiller, boiler, controls industry. Mathematically there is no difference between a pump and blower/exhaust fan. The only difference is the viscosity of the fluid that is moved. And fluid is moved by differential pressure. There is a massive pressure drop across a carbon filter. When you put that pressure drop on the suction side of the fan. It's the same as putting a piece of cardboard over the intake and blocking 40% of the intake opening. CFM plummets and the ability for the fan to make pressure drops like a rock. This also causes the air to slow down around the motor thus inducing heat rise in the motor and increasing bearing wear. The fan will get a bit more dirty quicker but you will also find out the fan will be much easier to clean and service. I've switched all the old big and heavy end suction heavy end suction blowers out for AC Infinity 6" units. The wife sews one end of the prefilter closed turning it into a bag filter. I then put the bag filter inside the carbon filter. Pull the open end of the bag through the slip flange and insert the fans discharge slip flange in. A couple of taps and it's sealed up. Cut a short lenght of 6" flex duct and put it on the intake side of the fan. Toss the unit up on the top of the tent and run the flex duck into the tent. The only pressure drop the fan see's is the tent. Putting the filter on the discharge side is called inducing head. That will back us up on the fan curve. But it allows the fan blade/impleller to remain loaded properly and the pressure created helps to over come some of the cfm loss.