Hi Your pebble shower floor is beautiful! We just got finished installing something similar. Sorry, but I can't help you with the grout problem. We haven't even started using ours yet . . . can't wait till it's finished.

I don't know enough about your shower to provide positive guidance. Dark grout is usually a sign of water absorption and/or intrusion. It can sometimes show a dark grout around the perimeter of a floor, sometimes with moisture wicking up and darkening the grout in the lower walls. But that usually occurs after more than just a few showers. It can show as a dark ring around the drain. Sporadic dark spots on the floor could be due to slow draining "bird baths", or slight irregularities in what should be a nice continuous floor slope from wall to drain. Built-ins like benches can be hot spots if they were improperly detailed during construction. It's tough to say what your problem is. The typical first question is: Did they install the waterproof membrane in the shower floor on a sloped surface or was it installed directly on the flat subfloor? An overall photo of the shower might help.

I have a unique "problem". When we built our house in 2007 I picked out the grout to use with our tile - which of course they didn't use. I had picked out the grout to use which would "blend" with the tile, so the tile would be the focus, instead of the grout. My husband was away the weekend they installed the tile (of course) and by the time he got back over the weekend, the tile & grout was installed - the grout being quite whitish, against Continental Slate - Egyptian Beige tile. The effect being, the grout was very noticeable instead of blending in with the tile like I had picked. Having said that....now 2 years on....the grout in the main usage areas has "weathered" to the point that it is now the color I wanted it to be, but there are still areas that are "whitish", which doesn't look so uniform now. Guests don't notice it (or maybe they don't say anything?), but I do. And it bugs me. So I have 2 questions: 1) What can I do to color the remaining grout so that it is more uniform? (No treatments have been applied to the grouting) 2) Once I get the coloring to the uniform effect that I want, I have heard varying comments on sealants. Experts have told me it's not worth it; laymen swear by it. Who is right? I don't mind the effort: Down on my knees with a toothbrush to apply; thank god it's only 700 sq ft on 18x18 tile LOL Your advice is sincerely appreciated!

Typically, the grout can vary depending on a lot of factors. Some Companies' grout is famous for that. An example is Custom's grout in light browns and grays. Another factor is the installer. Were ALL the batches mixed the same? Did they use too much water in some areas in cleaning the grout/tile? Are you on well water? Are the stars in proper alignment? Many factors contribute to this.....