I don't sweat the humidity so much anymore after DD started to stagger hatches. As long as it doesn't get bone dry or in the last week of hatch has some water in the tray, they will be fine. Put it simpily, we really don't change the water level for days 18-21. Just make sure the tray has as much water throughout the entire time as in the beginning. DD's hatch rate has gone up (expecially on shipped eggs). It's what works for us.
