When i've hatched eggs in the incubator, i've had them hatch as early as 2 days before and as late as 7 days after the expected date so dont open the eggs yet. There has been times where it began to look like none would hatch but they did
my incubator holds 24 hens eggs but i have noticed that when it is full to capacity the hatch rate is lower. Dont know why, but this happens with hens eggs as well as quail eggs. I seem to get a much better hatch rate when it is partially full.
I dont always candle them either. The quails i definately dont because you cant always see through them anyway. With chickens, sometimes i do if patience is getting the better of me.
mine is fully automated so i dont have the turning or humidity to contend with . There has been the odd time when i have completly forgotten to stop the cradle turning and it still been turning the day before the hatch day. This didnt cause any problems though.
Is this the 1st time you have used this incubator? It maybe that you have a few minor set up adjustments to make to obtain a better hatch rate.
The other cause really could be down to the eggs and the time of year. I use my own quail eggs and whilst we are still getting some now, they havent been mating for some months now.
I get my fertile hens eggs from Melton Market. I dont usually pay much more that a couple of pounds for 6. Some of the more sought after breeds cost more obviously. I've always had fairly good hatch rates (except for the times when the incubator is full to capacity). I suppose it is less of a disappointment when they havent cost a lot
Now, Melton hasnt been selling hatching eggs for some weeks now due to the time of year but come the spring there will be 1000's of all sorts, chickens, goose, ducks, guinea fowl, turkeys, quail, they even have peacocks eggs for hatching