Ken P

I would try soaking in a bowl of filter cleanse overnight. Fill bowl completely and cover tightly. Turn bowl upside down to submerge scum balls completely in the solution. Rinse the next day in clear water or place in dishwasher or washer machine on a rinse cycle only without heat dry. I haven't tried this yet but I'm about to as i have saved up a few used scum balls which I'm ready to clean.