Review on Lacidoll Large Room Whole-house Humidifier - 1000 sq.ft., 4.2Gal/16L Top Fill Cool Mist Ultrasonic Humidifier - Quiet, 1000mL/h Output with 360° Mist Tube - Ideal for Home, Office, Workshop, Greenhouse, School - White (1 unit) by Sarah Codina

My son and I each bought one for our home. They worked very well and we were both impressed with the performance of the device. The problem appeared about 3 weeks later. We both have central ventilation and air conditioning systems in our homes. Although the systems and layout of our homes are different, we faced the same problem. After some research we found that using the "ultrasonic" process in a "hard water" humidifier produces a very fine white powder. You'll see this mentioned by some of the other reviewers. If you have a central air conditioner with removable filters, this white powder will clog the filter. My son's filters clogged in about a month and mine took 3 weeks. These filters have recently been replaced. They were so clogged with powder that the oven wouldn't work because not enough air circulated through it. If you use electric baseboards or radiators, this humidifier is for you.