Good or no Good?

It's better, as I'm sure you've realised now, to wait until day 7 before you candle and day 10 before you discard any clears. That being said, I recently hatched some eggs under a broody that showed no sign of life until day 14 and hatched out perfect little chicks on days 19-20. With some eggs are just hard to tell. Leave them a few more days and candle again. While you're at it, if you see any eggs that looks like they might be going off, give them a sniff. I know, it sounds weird, but it's a fairly accurate way of telling if they are going off in there or not. On exploding eggs, all I can say is I've hatched 100's and I've only seen it once, under a broody, poor thing! So the odds are pretty slim. Best of luck with your hatch!

 

But don't only rely on your nose, candle them and if they look iffy, sniff them to check as well. An off egg does smell quite strongly, even if intact. I did some digging quick, while we're on the topic of bombs, here are the causes:

• Dirty eggs from nest. Dirty nests.
• Floor eggs.
• Eggs improperly washed; eggs wiped or cleaned with contaminated cloth or buffer.
• Dust from breeder house, cooler, transport, etc.
• Water condensation on eggs (sweating).
• Water sprayed, fogged, or splashed on eggs; eggs dipped in contaminated solutions.
• Contamination from earlier exploders, leakers, or broken eggs.
• Contamination from handling eggs with dirty hands or equipment.
• Contaminated setter flats, air filters, water (humidity) system.
  

Though, if you are guilty of some of those, it doesn't mean you are going to have problems, it just increases the chance. Splashing water on the eggs for example, setting eggs that are not 100% clean, increases your chances of trouble, so always be as careful as possible when handling and setting hatching eggs.