Apalus Ultrasonic Cool Mist Humidifier 1-Gallon Water Tank with Variable Mist Control, Automatic Shut-Off, Soft Night Light Options and Smart Remote Control (Black) Auto shut-off when water reaches minimum level, safe and reliable. 1 Gallon water tank design runs 24 hours on one filling. Humidifies rooms up to 300 sq.ft. If mist does not spray out, please check the humidity setting, please make sure the humidity set higher than the air humidity, otherwise it stops working automatically as designed. We recommend 40%~60%RH as it's the most comfortable humidity rate for human health. Produce rich anion negative ions healthy air, with 360 degree free rotating outlets. Please check if the rubber ring of the tank is in the right place, please try to tight it well when use the humidifier. Automatic moisture balance system helps to keep the ideal constant humidity. This model have 3 settings from approx.150 ml/H-350ml/H to select the amount of the mist, when you set it to the highest mist spray, you might hear the water dripping, but noise controlled &lt; 35 dB(A). The remote control helps you operate the humidifier from almost anywhere in the room.