O.K. - got my first two boxes of eggs today. In the meantime I've researched egg incubation to death and am even more confused than when I started. Kind of like when I first got baby chicks and every article gave different advice. I ended up raising them as close to natural as possible - without fancy brooders and free-ranging from very beginning - although in fenced-in quarters for the very young babies. Oh yeah, my question. I bought a simple HovaBator - still air model. Only one farm co-op in town and one feed store and this was my one and only option. Anyway, it has two red vent plugs in top only. Can't seem to find a consistent article that says whether to leave them both closed initially or one closed or both open near hatch times. I am finding articles that say there should be open vent holes on top AND bottom of bator for proper ventilation and that eggs must have oxygen flow or they will die. So for any of you who have used the HovaBator still air model - please advise - both vents open, closed or mixture?