Going to attempt the muriatic acid in a spray bottle approach to this problem. I have a few questions:
1. Its a 5 water to 1 acid mix?
2. What does it do to the grout?
3. I intend to be in the pool when I do this as I can't see that sort of dilution causing any problems. ie: Will not be worrying about the family jewels being exposed.
Any other tips?