Do a 24 hour bleach bath (10% solution) to kill off everything followed by a good rinsing, then a soak in a bucket of RO water over night. Then a 100% vinegar bath for no more than an hour... about 45 minutes should do. The first time I did it , I soaked for 3 hours and that was too much. It made the rock very crumbly, with bits flaking off everywhere. Then another rinse and a few soaks in RO water. Use a powerhead to circulate everything in your bucket or container for each part of the process. I chose the vinegar method cause it's winter and cold outside. I was able to do the vinegar method in the house. Also, I didn't want to deal with the poisonous fumes when using the acid.