I candled last night, am on day 20. Storey's Guide says to candle day 19 to check viability and get rid of dead eggs before they get stinky/explode. These eggs were all developing when candled day 8. They were dark, could see a few vessels and light shining through at the pointy end. The air cell was not big enough, so I have lowered humidity. Some seemed more dark than others. One had only about 50% of the egg dark, but could see vessels. I am confused. Maybe my candler is not good enough (box with a 60 watt bulb covered in cardboard with a hole cut in the top, I am laying the eggs on their sides). Help me please experienced duck hatchers. Thank you.