Early on in the life of my pool the tile grout emitted white streaks that I am pretty sure is calcium dissolved out of the grout. Didn't know about CH or CSI back then. I now estimate that the water had a very negative CSI back then.
I see that the proper way to clean this is full drain/acid wash. I've tried straight pumice stone. It gets the heavy stuff and the streaks down the faces of the tile but the grout still looks white-ish.
So here's my idea. Since an acid wash is a spray consisting of MA, what if I dip a pumice stone in 14.5% MA and then scrub the grout (with gloves, eye protection, etc). Then rinse. Would that work? What are the risks?