What is the best way to sterilize your nebulizer pieces (the mouth pieces and the pieces the meds go into)? I usually just put them in hot water for an hour then rinse them off but I am finding that they don't seem very clean even when I do that. Should I be using a special kind of soap or alcohol solution instead? I head that maybe white distilled vinegar helps??? How does everyone else do it, please let me know, Thanks!!