The unit is effective in putting moisture into the air but is the noisiest humidifier that I have ever owned. I would not reccomend this to anyone and would take the unit back to the store from which I purchased it but i waited too long. And, people should realize just because it is a filter free unit DOES NOT mean that you never have to clean it. You have to clean it regularly. In fact the instructions suggest you clean it DAILY. If you clean it at least weekly with a weak solution of bleach it seems to retard any yucky growth.