I have a home-made incubator. Maybe it isn't the best device in the world, and I worry all the time that its quirky personality is going to kill my ducklings. I've been through two thermostats on it, and I've made some other adjustments. I am hesitant to tell you that my incubator works well, because I have 8 eggs in lockdown and I don't want to jinx the hatch. The egg in this photo hatched into a healthy duckling about 5 weeks ago.

I am telling you all of this, because my worrying personality made me study how my incubator really works. I put a bunch of different thermometers and hygrometers in the incubator (in different spots), and every 30 seconds, I'd jot down all of the readings. Here is what I came up with:

My incubator runs on about a 17 or 18 minute cycle. The temperature falls, the thermostat kicks on, the heating elements heat up, then the thermostat kicks off, the heating elements dissipate heat until they cool down, then when the incubator cools enough, the cycle starts over. You can see why this thing could drive me crazy. But I know the average temperature, and I know how long it is too hot, and how long it is too cold.
So maybe your incubator cycles like mine? What kind is it? I know I felt a lot better about the temperature readings I was seeing after I had figured out how the incubator cycled.
I am telling you all of this, because my worrying personality made me study how my incubator really works. I put a bunch of different thermometers and hygrometers in the incubator (in different spots), and every 30 seconds, I'd jot down all of the readings. Here is what I came up with:
My incubator runs on about a 17 or 18 minute cycle. The temperature falls, the thermostat kicks on, the heating elements heat up, then the thermostat kicks off, the heating elements dissipate heat until they cool down, then when the incubator cools enough, the cycle starts over. You can see why this thing could drive me crazy. But I know the average temperature, and I know how long it is too hot, and how long it is too cold.
So maybe your incubator cycles like mine? What kind is it? I know I felt a lot better about the temperature readings I was seeing after I had figured out how the incubator cycled.
You're right. Besides the normal diffuse look of an older embryo (btw - how long do they stay "embryos" anyway?) my flashlight batteries needed a recharge. I did a full candle & purge of the bantam clears & quitters last night and ended up with 5 of the 16 being pretty clearly viable - the same number I thought I probably had the day before the temp dipped. And the one that had been in question had de-veined enough to be sure that it was time for it to go, too.
Then, after the incubator being totally stable all night long last night, we left the house for a few hours today and came home to 105 degrees. Ack! what the heck? The room temp has been between 70 and 72 this whole time, so that can't be the problem. I'm just hoping that it hadn't been that hot long enough to do much damage.
How long does it take to see if you've baked the poor ducklings? I peeked at a couple this evening and could see movement in one of the older eggs and heartbeats in a newer one, but also saw a couple of questionable eggs. Then again, I haven't gone through the newer batch in any systematic way, so I don't know whether those eggs were ones that were already seeming pretty unlikely.
Christy