When I 1st started using grow tents I ran into my tent sucking in (Negative pressure) at dark period when I closed all my side vents to stop light leak in my flowering tent. The only reason I closed all my vents is because I grow in my bedroom, and don’t want any of my TV light or lamps to disturb my plants.
So I added in 2 x 6 inch ducts with couple bends on the side ports of my tents to relieve the negative pressure and added either panty hose or carbon filter on the ducts to help with dust and reduce light. I have no high humidity, or light leaks since. Hope this helps.