You should always at least have one vent partially open. It allows the exhaust fan to pull fresh air in. During veg I leave one all the way uncovered. During flowering I cover it about halfway so there’s negative pressure from the exhaust fan and the smell goes through the carbon filter instead of directly into the lung room.
It’s a learning process. You get better as you go along. As knowledgeable as some growers here are I’m sure everyone learns something new from time to time.
