Okay here's the deal. I have a laundry room that I use for growing but I need some expert advice on what to do for ventilation and or co22. I'll say right off that I'd rather mot use co2 because I don't want to spend the money on it but I would if I thought it would really really help. From what I understand, if I have a good ventilation setup, I don't need co2 that bad. Conversely, if I have a co2 tank setup, I don't really need great ventilation. So let's try to stick to the former anyhow. I have a 4â€ vent hole where the dryer hook up would be. I can use that for intake, be it passive or active, or I can use it as an exhaust but then I wouldn't really have a place for an active intake. However, I take it that if I did use it as an active exhaust, a vacuum would be created that would be drawing in fresh air from places where the room is not sealed properly. I probably have, cumulatively, 30-40 square inches of places where air could be drawn in from the basement air. Also, I could, if needed, drill some holes in the ceiling and exhaust into the attic so that the heat can be removed from the top of the room as opposed to 18 inches from the floor where the dryer vent is. This room is at the edge of the house and the nights and days can get down into the low teens at the very very worst though usually it's between 25-55 outside in the winter. I can add heat as needed at night but I'm afraid that if I use an active intake during the day, I will be bringing in too much cold air. I am willing to get a controller for that issue. I just want some opinions on what to do with this room. Money is not so much the problem as is my inability to come up with the most effective solutions. Thanks in advance for any input. I've been racking my brain over this for a while and I'm not getting anywhere. I need you guys (or girlsâ€¦)!!!!