I once read about something that can cause fully formed chicks to drown during pipping but can't recall what it was. My last hatch was around 80% success but of the ones that didn't hatch after an additional 3 or 4 days in the bator I decided to throw them out. I had to crack them open just to see and what I found was 4 more fully formed chicks that were dead. Could this have been drowning during the pipping stage? What are the causes for this?