I keep my vents open and just watch the humidity closely. Chicks use a lot of air when they hatch, so closing the vents can sometimes reduce the amount of oxygen enough to effect their health. I have done it both ways, and leaving the vents open does seem to make a difference.
Thanks
I have been bad and candled the eggs on day five not day seven like I normally do but heck who cares. I have 3/5 buff orps that are showing veins and 3/7 gold laced crossed to buff orps also veining. So happy dance happy dance.....