I was candling eggs a few days ago on day 18 and was noting a disparity between air cell sizes. I am currently incubating bantam, large eggs, and mid-sized eggs more on the small side. The smaller eggs seemed to have better air cells than the large eggs, who had small ones for being so late in the game. I know shell thickness and porosity have something to do with it, and the large eggs (Bielefelders) have strong shells and aren't very porous. I wonder also if their large size increases their surface-area-to-volume ratio. without doing the math to prove it. For those that have incubated with large air cells and small at the same time, what's the best course of action? I have two incubators, I can try running one with large eggs only.