This is one of the sites I like as far as incubating advice. Your incubator will come with instructions but that is pretty basic. A site like this helps.
Texas A&M Incubation site
http://aggie-horticulture.tamu.edu/...e-Cartwright-Incubating-and-hatching-eggs.pdf
An important thing to remember is that the things in sites like this are guidelines, not absolute laws of nature. If you follow the guidelines perfectly, you are not guaranteed a perfect hatch. If you violate some guidelines you are not guaranteed a lousy hatch. All the guidelines do is improve your odds. I assure you many of us violate some of these guidelines regularly and still usually get good hatches.
An example. The A&M site gives temperatures the eggs should be stored at, without looking that's probably around 55 degrees. I don’t have any place that is that temperature. If the heat is in, my house is 68. If the air is on, my house is 76. I’ve had some really good hatches with eggs stored like that. I’ve had some bad ones, but I’m not convinced the storage temperature was the cause.
It is supposed to be a big no-no to store eggs in a refrigerator. Some people in hot climates store eggs in a refrigerator and still get good hatches. It’s the best that can do. Just do the best you can reasonably do and it is probably good enough.
Something else when you look at these sites. Many of them are geared more toward commercial operations instead of the home hatching like us. When you see things like fumigation, just blow it off. You are not going to fumigate. But the takeaway from that is that you need to start with a clean incubator. That’s important.
A. T. covered pretty well what I’d look for. A forced air is one with a fan. Those are easier. The still air or thermal air are trickier. An egg turner just makes it so much easier. I even store the eggs I’m collecting in the turner. Just take it out and plug it in. You want that visibility. You need to know what is going on in there, especially during hatch.
My Genesis Hovabator 1588 came with a plastic tray at the bottom that has reservoirs in it to hold water. That makes clean-up really nice. But that brings up a basic difference in the Hovabator and
Brinsea. The Hovabator is probably Styrofoam while the
Brinsea is hard plastic. I only hatch maybe twice a year in an incubator. If I were hatching much more often, I’d get a
Brinsea. They are more expensive but they are easier to operate and clean up. So another criteria I suggest is how often do you plan to use it.
Some interesting things I’ve learned. The commercial operators that use incubators that hold maybe 60,000 or even 120,000 eggs at a time and hatch 1,000,000 chicks a week usually get about a 90% hatch rate from the eggs they set. About half of that is that eggs just don’t develop to start with, maybe infertility, handling, storage, or something else. The other half of the failure is due to problems during incubation. Don’t expect to consistently get 100% hatch from the eggs you set. It’s really nice when it happens but don’t expect it every time.
No two incubators are the same, even the same make and model. You often have to learn how to tweak each individual incubator, maybe temperature setting or humidity. Different times of year or just moving it across the room can change things. The good news is that you have a wide range of things that do work. If someone comes on here and tells you that you have to use a precise humidity or civilization as we know it will forever change, you might want to get a second opinion. Try to be consistent so you have an idea of what to change if you need to change something.
If your eggs stop developing during the first week of incubation, that probably had something to do with before you set them in the incubator, storage, fertility, health of the parent flock, something like that. If they stop developing during the last week, that probably had something to do with your actual incubation.
No two eggs are the same, even if laid by the same hen. Thickness or porosity of the egg shell, thickness (viscosity) of the egg white, even basic size of the egg can be different enough to change hatching. You may get an egg or two that looks like the humidity was too high during incubation while the rest hatched fine. That’s not a cause for panic. You might want to teak it a bit, but don’t go overboard if the majority of your eggs hatch.
Don’t get too hung up on the 21 day thing. It’s not at all unusual for eggs to hatch a couple of days early or late. There can be a lot of different reasons for that.
I’ve probably made this sound complicated or hard. It’s not. Hatching is not a precise science. As long as you get in the ballpark for most of these things, you will hatch eggs, often a lot of eggs. You are dealing with living things so no one can give you any guarantees, but this is something you can do.
