I hope you can help me. I have a resort in Indonesia with a freeform pool (320,000 litre capacity, max 3m depth) and tiled in small glass tiles.
Recently a new member of staff started cleaning the walls with wire wool (!!!!!) and has naturally scratched them. They also then topped the pool up with water from a bore hole, not the fresh water that we make ourselves. The result was naturally algae.
We try not to use chlorine, we use a combination of Ozone and UV as we have to backwash into the ocean. But we will shock chlorine if required. This time we have had to use chlorine and acid. We have cleaned the water, but the wall tiles (not the grout) have stayed green. I think the algae has fixed to the tiles where the wire wall has damaged the glaze.
Do you have any suggestions? A team of us are going in today with scuba gear and soft brushes, but I don’t hold out much hope.
Any advice gratefully received.
If chlorine and acid didn’t take the green off the tiles (and they would if it was algae) I would use ascorbic acid/vitamin c to see if it is metal residue that has adhered to the tiles. Does the water from a bore hole have mineral/metal content? Do you run a pool heater at all? Copper from pool heater pipes can stain pool surfaces if the water chemistry gets too acidic and starts to etch the metals. If it is metals a product called StainFree (which is ascorbic acid based) would remove the stain from the pool walls and then a metal remover would be needed. If that is not it, then the tile may just be damaged and need to be replaced.