I am incubating some eggs in my DIY incubator that is pretty much air tight. I know this may be a silly question, but do the eggs need to "breathe" or anything? I do have some vent holes I can open but this thing has been locked up tight for the first 4 days. I think more than anything I am just worrying about my little brood because there is nothing more to do other than sit on my hands until day 7 or 8 for candling. Thanks!