duck eggs

[spamee34]

I have a still air incubator it's styrofoam and it keeps loosing it's humidity . I have only been able to get it up to 47 percent how can I raise it more and what exactly should it be for duck eggs?

 

[MagsC]

Wet sponges or paper towels, though sponges work better...
I kept the humidity from 55 to 60 for duck eggs the first 25 days.