Well for the first 25 days it was in the 50s then I put them in the hatcher which is at 67. They all still have their yolks etc no blood just liquid!! First time hatching ducks think it'll be the last time aswell to much stress with ducks lol cute though!
I used to follow the conventional wisdom about keeping humidity for hatching duck eggs at 55% until lockdown but had problems with goo, so now I dry hatch (aiming for 35-45% humidity until lockdown). I also mist and cool the eggs, and I believe the misting helps manage the moisture inside the egg better than just depending on external humidity. If you're interested in dry hatching, this thread may be helpful: https://www.backyardchickens.com/t/715902/humidity-for-hatching-duck-eggs.
Best wishes!