I have a homemade incubator and am wondering if there are guidellines as to how much fresh air should be introduced into it during incubation. I have 2, 3/4 inch holes in the bottom and 1, 1/2 hole in the top. The top is maybe a more positive pressure because of my air flow arrangement. This is a topic that I have not seen discussed much, but I expect air requirements to go up as the chicks develope. Any guesses as to how much flow we should have, and how to know if I have enough!!