You're not failing! If 50% of incubated eggs hatch, you're doing fantastic! It's a learned skill (for humans and for non-broody ducks), and it isn't easy.
There are a few things to keep in mind:
1. Not all incubators are created equal
2. Putting fertilized duck eggs of different ages in an incubator can mess up the humidity and the
CO2 levels - that's why some people buy fertilized duck eggs from hatcheries. The age problem is solved, but the hatch percentage is still pretty low - maybe 70% is a good number?
3. Incubating duck eggs is
hard.
I've got to go do stuff (I'm taking a well deserved break, but it won't last forever ;) ), but I'll check on this
thread later.
Do you have
Storey's Guide to Raising Ducks? I feel like I'm shilling for this book... . Anyway, if I recall correctly, there's a great section on duck egg incubation. I'll see if I can find it later if you don't have it.
Don't give up! This batch might not make it, but that's part of the learning process. Don't give up!
:) Beth
Apologies for typos and poor grammar - not proofreading...