Equate Ultrasonic Humidifier User Manual -

You can, but minerals will create white dust (calcium powder) on your furniture and eventually calcify the diaphragm, reducing mist output. Distilled water is best.

No. It uses a piezoelectric ceramic heater to warm the mist to around 104°F – warm to the touch but not scalding. The mist is still safe around children when used as directed. equate ultrasonic humidifier user manual

That’s bacteria or stagnant water. Perform a deep vinegar clean immediately. Always dump standing water daily. You can, but minerals will create white dust