more ventilation questions?

[keylime]

Well, I don't run the fans during dark. After 30 years, I see no difference.

I think that depends on how big a room you have, and the conditions outside.
If you had a small cabinet and its more or less sealed..... if you're running hydroponics your humidity will jump to the point you may be inviting powdery mildew and other kinds of disasters. Even if the humidity is high coming into your cabinet, ventilation will be better than just having the plants sit there cooking or sweating.

keylime