Has anyone ever heard of using permanganate of potash to clean the patio. B-in- L who is a professional gardener with years of experience certificates etc has suggested we use this to clean algae off patio but I can't find any info via google ??? so I thought I would ask the other experts.
I have bought it & it says on the tub to be disposed of as hazardous waste, is a danger to the environment & can harm fish so I don't want to use it unless anyone knows anything to the contrary.