Day 10 blood rings mystery

[Cape Cod Egghead]

I'm using a forced air Hovabator with an egg turner, loaded with 42 chicken eggs from 3 separate sources, all with very good roo to hen ratios. Eggs were incubated within 7 days of collection, and were kept in room temp conditions before set. I resisted the temptation to candle early on, and monitored temp and humidity regularly. (Up to 5x per day as they are in my little classroom on our first floor. lol.) Temp has been consistently between 98 and 100, without going over 100 at all. Humidity has been right around 50% for all ten days. I DID carefully wash off some dirty eggs with warm water before set, which I have not done before, but I read so many comments on here from folks who do wash, I figured what the heck.
SO, I am completely at a loss. I candled and found what seems to be a clear majority of eggs with a blood ring around the interior circumference. (As well as no veining in these and just a floating blob of material inside.) Sorry for not adding photos, but there's plenty on here that look exactly like mine. Because the eggs were collected from 3 different people, and I am certain all three sources are feeding their chickens very well (including mine ) that seems to reduce possibility that it has to do with roo and hen nutrition, or handling issues (if most eggs from one source had problem I would suspect something about the handling of those eggs or something about the source.) So, clean incubator (run 2x last summer) no handling after 'bator loaded, so no bacteria introduced that way, no temp/humidity fluctuations... What am I missing?
If anyone has experience with this, I would appreciate any advice, tips, ideas. My only thought is to go back to good ol' dirty eggs for the next run.

 

[AZBootsie]

Class room in a school?? Any chance the heat is lowered in the middle of the night to conserve?? Maybe the room got cold and incubator couldn't keep temps up??

 

[Cape Cod Egghead]

Thanks, no - classroom in our house! I have been like a fussy momma hen over this batch of eggs because I have it right on our first-floor living area. (I usually hatch in the basement, with good hatch rates, but that has been in the summer.) I haven't opened the 'bator except to quickly add water and the first time I touched them was candling on day 10. But I do check temps a zillion times a day and it hasn't dropped below 98 and hasn't risen over 100.

 

[SierraView]

I believe washing the dirty eggs was the reason you got the blood rings. I keep my chickens nest super clean and rarely have a egg with more then a smudge. If I find any egg that's dirty I toss them, I won't even eat them. I've seen some people wash them using oxine I use it to clean my incubator but never washed eggs before so not sure the results.

 

[Cape Cod Egghead]

Thanks, I was looking suspiciously at the egg washing too, as I've never done it and haven't had this problem. I was thinking any egg smudges makes for more bacteria in the 'bator, but I searched egg-washing in here and found an even amount of comments for and against. Still feeling stumped, but I will keep some hope alive for those eggs that have good veining and normal development, then try again as soon as this batch is done.

 

[minpinmama]

When I googled pictures of incubating eggs one web site I came to showed pictures of good and bad eggs.
The ones with the blood ring was said to be bad and a sign bacteria got into the egg.

http://howtoincubate.com/index.php?option=com_content&view=article&id=54&Itemid=56
Dead embryo
If the egg was fertile but the embryo has died then you will see a blood ring around the yolk or possibly a dark spot dried to the inside of the shell depending on when the embryo stopped growing.
Note that dark or brown shelled eggs are more difficult to candle than white or pale shelled eggs.



[FONT=Arial, Helvetica, sans-serif]Pictures on this website:[/FONT]

http://shilala.homestead.com/candling.html

I had 17 eggs shipped to me, when I candled 15 were not good, 10 were just a plain yoke and 5 had the blood ring, no
real see-able chick except for one had a tiny weird thing which could of been a chick on day 1 or 2.
2 are still in the incubator.