Cleaning CWGC tablets
ATR43 My apologies, I don't often get the chance to visit this site and missed your message. To the best of my knowledge, CWGC use a mild solution of bleach to clean algae and soil splashes from Portland limestone. If you think about it, with the number of stones they have to maintain (the number's in the back of my head somewhere and these days will probably have to remain there) anything resembling a commercial product would be ruled out on cost grounds. Anyway, they've been cleaning them for eighty-odd years, long before anything more sophisticated was available. It's what I use and seems to do no damage.