True enough! the unfinished area that I want to utilize as the finished "rec room" is about 3000 CF. I think that if I can cycle that volume every 10 minutes (just guessing here, but that would be a good starting point) I could make a relatively smoke free environment for smoker/nonsmoker comfort. That translates to about 300 cfm cycle time. I am willing to install the duct work myself and install the fan as well. Someone suggested I use a house fan (one of those you put in attics) and run the air through an HEPA furnace filter. A previous suggestion from a bro lead me to a site that sells filter systems but they didn't handle the capacity I was looking for. Maybe my cycle time is unrealistic. Haven't found a good resource for planning a smoking room yet.