Duck Egg Air Cells Too Small

[MerryFeather]

I have 5 duck eggs on Day 24 of incubation. I am using a new incubator (Brinsea Maxi Advance) for this group of eggs. I have been letting the incubator sit at about 40-43 percent humidity for the whole time since that is what filling the one side of the cup maintains. It has been stable. So it surprises me that the air cells are so small and the eggs seem to have more fluid in them than my previous eggs at this stage. I thought it might be that the vent holes are so much smaller than the NR 360 that I am used to. However one egg is a smaller egg and from a different duck. It has an air cell that is looking too big. The 4 that have small air cells are all from my 1 year old Blue Swedish. Because the one egg has a large air cell it makes me wonder if the problem is the eggs from the Blue Swedish. Is it possible that her shells are thicker or membrane different and her eggs just don't lose moisture at a good or similar rate? What could be causing this?

 

[HollowOfWisps]

I've found that charting air cells isn't always an exact science. I've had some look like they were too small and then by the next day almost double in size. I've been hatching every spring for a few years now and I stopped paying attention to the air cells unless I'm looking for internal pips. I now instead weigh before I set the eggs and when I candle during to check for around 14% water weight loss. Much more accurate than eyeballing the air cells.

 

[MerryFeather]

I've found that charting air cells isn't always an exact science. I've had some look like they were too small and then by the next day almost double in size. I've been hatching every spring for a few years now and I stopped paying attention to the air cells unless I'm looking for internal pips. I now instead weigh before I set the eggs and when I candle during to check for around 14% water weight loss. Much more accurate than eyeballing the air cells.

I did weigh them at the beginning and again a few days ago. The little egg only needed to lose 1 more gram in almost a week. The others needed to lose double what they did I think. They are supposed to go into lockdown tomorrow. I've never had eggs that had this problem before and they were all incubated at a higher humidity by 10 to 15 percent more.