positive or negative pressure?

which pressure is better for growth, positive or negative and why?

i think they say to use negative simply because it won't allow smell to leak out if it's sucking air in thru the cracks. that's my guess.


i'm using an active intake which forces air into my room. i have a passive exhaust so i am running positive pressure. enough to push the door halfway open when cracked.

thanks, guess ill have a room le peu too. much appreciated!