Take it from a guy who's been there, you want to keep that fog REAL HIGH to get a cutting to root, then later drop it down lower (the water level ) so you dont drown roots as they get bigger, or do some sort of coil up of roots (what i do) ocationaly..
anyways, here's what happens if the mist isnt high enough:
Lost all but 2 plants, but honestly i didnt fill this thing up or even check on it very often, just happend that the water got too low, a little attention will keep them looking like they did before (huge and fast!)