I'm having a problem and it's worrying me. My eggs are at 16 and 14 days. The air sacs aren't as big as they should be. I just put in more water and added a sponge. They are alive and growing but the air sac isn't. And no, I don't have a reader for humidity.
this is most likely a dumb question but you are measuring the air cell at the big end right? and you should only be worried if the air cell isn't a 1/4 of the total egg if the air cell aren't big enough you need to remove the water and sponge not add it. the only time humidity is increased is when the eggs are on lock-down.