I am constructing a grow room within an unused room in my basement. Sort of like a tent but wood, framed in and plywood walls. Pulling air into the room through the cool tubes then out of the room and outside. Is this sufficient or should I be pulling air from outside as its fresher air?
you need to replace all the air in the room with fresh air ever 5 minutes or so. hope that makes sense, im rather stoned.
If your cool tube is closed off, it doesn't matter if the air is fresh or not. The way I have mine set up, I have an exhaust fan and ducting attached to one side of the hood, blowing air straight up into my attic. Other side of the hood is left open. So it draws the hot, old air into the hood and out of the room, causing cool, new air to come into the environment through passive intake.
That being said, I decided on this method of venting based on a lot of research, not on experience. I just got my space set up like that, and haven't taken it through a full round as of yet. From the looks of things, it seems to be working well so far.