Ok so I am setting up my closet grow. In my 4x8 closet I have a 36x24x60 veg tent and a 40x40x79 flower tent. What I was thinking was a 4" duct fan pulling air out the top of the veg tent, a 6" duct fan pulling air through light hood and out top of tent both venting into the closet. Then use a good quality 6" carbon filter to a 6" inline fan and out to my laundry room. As long as I get good negative pressure smell should not be an issue. What I am not sure about is with negative pressure in the closet will I still be able to get negative pressure in the tents or will they fight each other?
So how are the fans setup again? I see you are asking if you can use a 4" fan out of your smaller veg tent, but when you state using a 6" fan, you just simply say "tent". I'm assuming you meant the 6" fan is for the larger flower tent. What is the order of air circulation? Example: Air comes in through hole in closet door -> Air come in through hole in veg tent -> Air get's sucked through carbon filter -> etc...
If you plan on closing the closet door, you will need a decent sized passive intake opening. I doubt the crack under the door will be nearly enough. Otherwise you will have pressure issues.
I do have a large vent in the door. Air flow should go 6" pulshing air out of closet while veg and flower tents vent into closet.
So the tents vent there air into the closet which in turn vents out through the hole. How does air get into the tents?
Well I have an open vent in the door that lets in fresh air. Where I am stuck is if I have neg pressure in the room will I be able to get neg pressure in the tents with my set up or will I need stronger fans for the tents. I am using HVAC booster fans to draw air out of tents now.
It sounds like you will want positive pressure in the closet and then negative pressure in the tents. Sounds complicating. I would honestly just not even use the air in the closet. Bring air from outside the closet directly to the tent and then exhaust it right back out of the closet again. That way the air in the closet isn't important.