I've been loving this hatch-a-long thread and seriously, I really want to hatch out some new ducklings now ...
However, I set 22 eggs Tuesday of last week: 19 ameraucana eggs (blue or splash chicks) and 3 ameraucana mixes. I candled them tonight and I could easily make out developing chicks in at least half of the eggs, but some of these eggs are really opaque. Maybe I need the room to be even darker? The incubator's display lights were still on next to me.
Here are two lively ones:
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And a number of them looked like this (excuse my cell phone photos!):
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Turning them, I could see a slightly darker side and a slightly lighter side, but making any veins out was impossible/I felt like I was seeing things. Is this normal? I hatched out ameraucana last year and I don't remember having this issue, but it was the first time I had incubated chicken eggs ...
I would imagine the slightly darker side you're seeing is the growing chick from your description.