I have a 3" unused pipe vent that runs open into room. I guess I would be best using it to "bring air in" as opposed to exhaust..... I figure the fresh CO2 and oxygen is more beneficail then exhausting. I think I would use carbon filter and exhaust air into larger area of attic. Yes, I have to figure best way to hang light. I also wanted to ask about a shorter veg time and going to flower earlier to limit height. Is that a beneficial plan and will that hinder "bud quality"?