First, consider ordering the mixed barnyard eggs if you have no choice but to ship, and order them from the nearest seller with a good rep and a decent price. If you can possibly do it, buy locally. Search the net for a nearby poultry club. Someone will sell cheap or maybe even give you mixed-breed eggs. I have several mixed breed birds that I got in just that way. They’re among my favorites. It’s no good ordering expensive purebred eggs until you’re comfortable with hatching.
Second, the recommended temp is 99.5. Much over that and your eggs may die. I’m guessing your thermometer is reading high and your surface temp (where the eggs are) is not that hot or I don’t think they’d have gotten as far as they apparently did. It may still be hotter than optimal, though, causing the chicks to grow too fast. (That is my speculation only.)
It does sound like they’re drowning from too much humidity. Weighing the eggs as FortCluck suggested will help you monitor moisture loss. You must have slow, timely moisture loss in the egg in order for the chick to develop properly and to give it an adequate breathing space for it to use during hatching, in the time between the internal pip (the chick breaking into the air pocket) and the external pip. It will also help you to trace the line of the air cell in pencil or felt pen on the shell when you candle. You should see a gradual enlargement of the cell. Too much humidity can also (I’ve read) cause them to grow too big without maturing sufficiently.
I feel confident this has been your problem. We have a very dry climate and I do add humidity. I try to keep it around 35-45% during incubation and 60-80% during lockdown. Make sure your thermometer(s) and hygrometer(s) are accurate.
Your incubator probably has several canals or channels which you can use to hold water. If the humidity stays too high, you may be using a channel with too much surface area. Go to a smaller channel. If too low, choose a channel with more surface area or use more than one channel. If you cannot seem to get the humidity high enough (as in for lockdown), you can add dishes with small pieces of wet sponge in them. Don’t add the sponges without the dishes, though. I’ve heard of chicks drowning by falling asleep with their little faces buried against the wet sponge.
I’m really sorry you’ve been having such a rough time. Hatching is a joy when you have a successful experience. It’s truly worth it to persevere. You’re gonna get this figured out—just keep trying. Mama hens don’t always do that well, either, so don’t get discouraged. You’ve got this!
