Yeah! If you can track down a brighter light you might be able to see something in the darker eggs. Out of the 48 eggs I have incubating now (14 of which are Marans), the only two I can't see in are some olive eggers. They are amazingly opaque. I am using a Milwaukee 14.4 volt work light with a...
Congratulations! A lot of people don't cull dark eggs unless they are leaking or smelling. Too many people have posted on here how they thought an egg was a dud, and broke it open to find a developing chick. If you're not 100% sure, leave it in.
For some reason I'm thinking that you can't post potos until you've written at least 25 posts. However, I couldn't find that in the FAQ so I could just be making things up. :D