Bests & Worsts Reviews from Amazon

I loved this diffuser when I first bought it less than 1 year ago. It produces a lot of mist and runs for a good amount of time before shutting itself off. However, the water tank is a one piece, completely closed unit that cannot be opened to clean. Mine is growing black mold inside of the tank which cannot be reached with any kind of brush to scrub it out! I've tried using different cleaning agents and hot water and then shook the tank vigorously to try to dislodge the mold but to no avail. Why would anyone design something that uses water & oil but cannot be cleaned?! I'm very upset to find that we've been breathing in mold while we were sleeping! I do not recommend this diffuser, especially if you have allergies! I've attached photos showing the mold growing in the nooks and crannies as well as on the inside of the tank. Serious unhealthy design flaw. :( 3-7-2016 UPDATE: I contacted the NOW company about the mold issue with this diffuser model. They sent me the phone # for the manufacturer of this model: Greenair 1-888-548-0040. When I spoke to the customer service rep, she offered to send me a new water tank after apologizing for the bad experience. So, if you're interested in getting a new water tank, call this customer service #. She also told me how to open the bottom of the tank to better clean it out. The oval shaped tube thing next to the fill opening comes out so you can clean the inside of the vertical opening. It's really tight so you have to wiggle it back and forth a bit until it comes out. This does not however, help to clean out the sides or bottom (inside) the tank, just the center, vertical tube that opens up to the small hole on the top where the mist comes out.