Need a little help with my pool tiles. These are the ones on the pool lip. They were originally light blue and had turned blackish with what looked like baked-on hard soot or grime. I've tried most of the tile cleaners and they were not effective.
Pumice seemed to do the job, however it was slow going and hard to get into the crevices (the tiles are "dimpled" to avoid slipping). What are my other chemical alternatives? Would muriatic acid do the job?
A photo is at:
TIA richard