Day 18 to Day 21

[ourtown]

First time hatching - my flock is 7 Black Australorp hens 9 months old plus 2 roosters - they are happy that way

I have a Hova Bator Incubator 1602n with a turner and fan

I collected eggs for a week - got 26. The Incubator seemed pretty stable - set to 99F 55 humidity using a digital thermometer - I could have set it to 100F but not the recommended 99.5F

On Day 18 I was ready for lockdown but one of the eggs was already chipping - 13 live chicks arrived by end day 19 - one didnt get out of the shell

Now it is day 20 and the other 12 eggs show no activity - they are brown eggs and I couldnt candle them with the lightbulbs I have

What do you think 12 eggs non fertile or failed development - should I wait another 4 days or eggtopsy one or two to find out ?

 

[ChickenCanoe]

Sounds like your instruments were off and that the temperature was high throughout.

 

[ourtown]

That was my first thought - I checked with my other household thermometers but I dont have anything that measures 1/10 degree

I have 2 walmart acurite digital thermometers - they all agree that the temp is 99F

I will try an oral thermometer from walmart

For the next batch I will use 98F

Eggtopsies showed from 26 eggs
13 hatched but one has a leg problem
1 failed to break out of the egg
2 died inside the egg when fully developed
5 died inside the egg during development at different stages
5 infertile eggs

I don't know if this is expected incubator behavior
I already have another batch running in a still air incubator at 100F
>Added more information

 

[ChickenCanoe]

Over the years, I've probably used 50 different thermometers. In my experience most were off by at least one degree, most are only supposed to be off by +/- 2F but I've had some off by way more than that. I had a thermometer from an incubator company that was accurate at 70F and off by 3F at 99.5.
Unless you calibrate or buy a guaranteed accurate thermometer, there is no way to know.
An oral may get you closer.
My go to best thermometers out of the box are Brinsea Spot Check and Thermoworks pocket digital super fast RT30IWA.