4x4 ventilation help.

Sorry i dont have pics yet will post them later.
In my 4x4, i have 2 plants in fabric pots that I just switched to flower with a tall rotating fan. I do have a 4in carbon filter with in-line fan, but I dont have it turned on because the tent then has negative pressure. I have all openings in the tent closed. So I figured thats my there's so much negative pressure so, To fix this i left a air flow vent open at the bottom of the tent and still there's alot of negative pressure. I dont thinking adding more fans will work or raising the speed on my tall fan from low to high will work either.
With my plants being in flower I dont want the smell to escape into my house. I have the tent in my laundry room. I want the air filter on so there's no smell but too much negative pressure, then if I open a air vent at the bottom of the tent and add a fan to bring in fresh air. And to combat the negative pressure, the smell will escape into my house thru the open air vent....sssoooo what do I do????

Get another inline fan and suck some fresh air in that son bitch

I use a 4 in Wye and 2 back draft valves. I also work in my laundry room.

Tie the exhaust from the tent into the dryer vent!
use the backdraft valves so the dryer air will not flood the tent and the tent won't go into the dryer.

The negative pressure is what you want.
Your tent will draw fresh air through the intake at the bottom, and expel it outside (and not back into the room).

Pacoson71 said:

The negative pressure is what you want.
Your tent will draw fresh air through the intake at the bottom, and expel it outside (and not back into the room).

Click to expand...

If you live in a place were smell is a problem than negative pressure is a must but i had a buddy using a duct booster fan at the bottom too bring air into his tent and a duct booster fan at the top too suck air out using no carbon filter.
There was no negative pressure and the grow went fine