My 6 plants in a 4x6 basement room started smelling quite dank by the 2nd month. I put in a 6" exhaust pipe vented out a 2nd floor eave. It was too noisy, so I upgraded to an 8" ACinfinity inline fan and 8" galvanized pipe. Speed 2 (out of 10) is enough now to keep the smell outside. It's whisper quiet. Part of the exhaust run is up through an interior wall, and that's the only noise, the air rushing through the 4x14 space between studs. I haven't put a filter on it, and hope I won't have to. If the wind is right I can smell it on the sidewalk out front though. Sometimes my wife complains when the aroma blows back into the house through an open upstairs window. I blame it on my neighbors, who are 3rd generation stoners. I often smell weed walking around the neighborhood anyway.
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For a while I was putting 1 plant in a dark corner of the attic at night so it could get 12/12 light/dark while the grow room was on an 18/6 schedule. When it got well into flower it was smelling up the whole house, so now I have to keep it in the grow room with the others. I have 2 photoperiod plants in flower, and the rest are autos, so they're all on a 12/12 schedule for now.
My wife is unfortunately not a stoner, so I have to keep the sweet aromas out of the house. I married her during a period of my life when I was not smoking because I was subject to random pee tests. Oh well, she has other merits.