If you use filtered water it will help and also.. I hate to tell you this but you should be cleaning it every day if you use it every day. I know it is a bummer but necessary. Bacteria and other things only need a small amount of time to grow and these things not only leave a film on things around the room, you also breath them in and guess where that film goes. Try cleaning it every night and use filtered water, I bet you won't have the problem anymore.