After use, the carb stone should soak in Alkali Brewers Wash or similar product for at least 24 hours. After a good long soak, rinse with warm water while attaching the stone to a CO2 line to push all residual material and brewers wash out of the stone's porous body. When ready to use again, it would be wise to do one more rinse then soak with sanitizer for a few minutes.