Winter hatching with the low end bators is tough for getting the humidity right. With that, I've had a decent amount of success using sponges, and most recently (this past weekend) I opted not to use sponges, and just filled the water chanels with paper towels when I set the eggs. The paper towels worked just as well wicking moisture into the bator for the hatching period, and I don't have to worry about sanatizing them...just toss, and replace when I re-set the incubator. However, since you arleady are at hatch time, just put some sponges in and leave it. The eggs should be fine. Even if you go over, there is too little time in the last couple days for moisture to build in the air sack to drown the chick.