Thanks for the ace advice Mike! The rest of the shower cleaned up nicely, even the glass, but that floor was tough. At first I used a high alkaline cleaner with a nylon brush on the walls, and a brass brush on the floor. Then I used an acidic cleaner around 2 pH or a little less on the floor with more scrubbing and rinsing, and I repeated everything on the floor several times, lots of dwelling, scrubbing, and rinsing. And this is what I ended up with
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It looked better immediately after I finished, but the minerals wicked up to the surface in just a few minutes. I set the customers expectations well beforehand so they were happy with it all. I was in that shower for way too long. I'm going up on my shower prices. They didn't opt for an enhancing sealer to temporarily hide the whitish remains in the grout. This is what it looked like before I worked on it.
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