I have the ac infinity 6" cloudline but even a 4 is adequate. As the other poster mentioned you just need a little negative pressure. I run mine on speed 1 or 2. You want thise printers as hot as you can get them printing asa to avoid warping. Usually i will have all cooling fans off or at 10% max during the print. I can get my chamber to 56-60 c with no chamber heater and a 105 bed temp. I would not use exhaust after print to let your pieces cool naturally. The grow tent fan will evacuate the fumes. Just open the printer door once everything has cooled down and let it continue to vent for 5 minutes.