I am incubating duck eggs, multistage in a Hovabator incubator. Everything is going well and all fertile eggs are growing well. Tomorrow is 21 days for five of my eggs. I draw pencil lines weekly at the edge of the air space. I do so while holding a flashlight to the egg so I can see the exact place where the edge of the air space is. I have drawn the original air space (quite small), the one week and the two week air spaces. I see the space growing throughout the week and I mark it on Saturday. ONE egg has not dehydrated at all for a whole week. All the other eggs in the incubator were dehydrating fine except for that ONE egg. A few days ago I dropped the humidity level from about 65% to about 55% just to help that one egg. All the other eggs are dehydrating faster than before and show greater growth in their air space (within good norms). But that one egg still isn't dehydrating at all! The edge of the air cell is exactly where it was a week ago. Not almost the same place, exactly the same place. During weeks 1 and 2 this egg dehydrated slightly less than the others, but not dramatically so. Now, during week 3 it has just quit dehydrating completely. The air space is staying exactly where it was last Saturday and it's been a whole week. All the other eggs show an air space that has grown considerably. The egg does contain a live duckling that moves around normally, the same as the other ducklings. I candle each day and all ducklings in the five eggs move around and are active when candled. Except for the tiny air space that is way too small for 21 days, the egg looks completely normal. I have tried washing the egg several times in tap water to try to increase the porosity of the shell. I have been afraid to try soap or bleach, so as to not hurt the duckling, but I am really worried as tomorrow is day 21 and this one egg has almost no airspace compared to the other eggs. Only one week left and there isn't enough air space for this duckling. What should I do? I can drop the humidity a bit more, but I'm not sure that would help. The air space has not grown AT ALL during the past week. Any ideas? Help!