I've seen many threads about cleaning stones between uses, but haven't found anything for if the stones were neglected. I went on medical leave to recover from back surgery, and was gone for a couple of months. I left my stones and a few other supplies in my massage room for the temporary therapist to use. When I returned, I not only found the stones still in water in the warmer (which stunk and had a slimy film and floaties, ewwwwww), but they also had many rings of hard water around the larger ones that were partially exposed. I have scrubbed and scrubbed the stones, I've boiled them with purifying essential oils, and am currently giving them a vinegar bath. But I'm having a hard time getting the hard water off. Has anyone had to clean their stones in this nature? What has worked? My next resort is scrubbing them with CLR or Limeaway, which I'd rather replace them before using harsh chemicals on them. Any insight would be greatly appreciated! Thank you!