If the level climbs too high, you can turn the mist down or off.
Advice For ultrasonic humidifier - The Inside
Rather than using a fan to blow air over the filter, the ultrasonic employ high-frequency vibrations to gently shove the water vapors through the humidifier and out into the room.
Sensible ultrasonic humidifier Plans - The Best
A note on this sort of unit is when your water is difficult, it's going to leave a white dust over furniture so it's far better to used sterilized water for anyone who is mindful of calcium in the water received from your water supply.