Air tight incubator?

Even with 6 clutches and 50 eggs in my 12 cubic foot red bull true cooler there's no issues.
Eggs do not need much air and even keeping babies after they hatch in the incubator poses no issue.
Opening the incubator every day or every few days is all the air exchange you need.

My incubator is an old fridge which I assume is pretty darn air tight. I only open my incubator once a week at most -at least until the end of the incubation.

I am also using and old freezer and I sealed the hole after I ran my wire into it. I go weeks without opening it. While the eggs are alive they are not breathing. Closer to when you are expecting eggs to hatch you open the incubator a lot more often so no danger of a baby not making after it hatches from lack of air.