I am building a homemade incubator and I have a question. I am worried about ventilation because I know i is pretty important to not allow suffocation by the incubator being to tight and not allowing exchange of gases. I was thinking of adding a small diameter fan with a timer set to cycle for 60 seconds every 8 hours etc. The question I have is would this setup be overkill ? Do you guys usually just drill holes in the incubator ? If so how many and what size do you guys use for a cabinet style incubator that holds 200 eggs. Any info would be greatly appreciated.