I don't think that marble mosaic shower floors are difficult to keep clean. Don't use anything acidic.

The more important issue re: marble mosaic shower floors is having them installed correctly - otherwise, you'll be disappointed because some of the tiles will look darker due to holding water. Marble is porous - much more than porcelain tiles.

The best installation method is to use them on a traditional mud pan (a water in - water out system). The is a professional who sometimes posts on Houzz who did extensive research re: why so many people were having issues with their marble mosaic shower floors. It appears to be related to the use of surface waterproof membrane systems (instead of traditional mud shower pans) + impregnating sealers.

Water vapor travels through the sealer and then turns back into water under the tile (the surface waterproof membrane prevents the water from completely leaving the shower pan - traditional mud pans allow the water to flow downward - away from the tile - and exit through the weep holes in the drain). It becomes trapped because the sealer keeps the water from traveling back through the marble = the water is only able to travel through the grout = it takes a long time for the pan to dry out.

In my experience, marble mosaic shower floors are VERY difficult to keep clean, especially if you have hard water, like I do. They accumulate mineral deposits in the grout and the hard water etches/wears away the marble. I have basketweave black and white marble floors both in the shower and the rest of the bathroom, and the shower floor looks awful. I need to have a marble cleaner/restorer come once a year to clean and refresh it, including re-caulking. I would never do it again.

Random thoughts:

- Google problems with marble on this board. If you're dead-set on that look, I'd suggest porcelain-look marble instead of the real stuff.

- You might want to color your hair in the future. It only takes once for someone to use the wrong cleaning material, and the damage is done. Ask yourself this: Why do marble cleaners /restorers exist?

- Consider a shower pan for the floor. Tile floors are highly dependant upon your installer's skill -- and you can't know for sure until the work is done. A shower pan is less expensive /lasts longer /is guaranteed to have a perfect slop /is easier to clean. I have a shower pan in my bedroom, but a tile floor in the hall bath -- the hall bath has a "high spot" that always feels wrong under-foot. You can still have tile walls with a shower pan.

My shower floor is done with 3x14" matte tiles laid in a herringbone pattern. Yes, the tiles needed to be cut in what my tile setter called an "envelope pattern" for drainage. But he did it so thoughtfully that the envelope cuts enhance the herringbone.

I tell you this not because I think you should necessarily do the same, but because while choice of grout colour, tile size, primary setting pattern are important to the final look; the most important element is a skilled tile setter. Mine drew out the cutting/setting plan on paper and shared it with me so I could see exactly what I'd be getting.

so what kind of tiles do you have, Jennifer? marble, porcelain or ceramic? The most important factor to me is what type of tile you have? Of course a skilled tile setter is of utmost importance.

My floor tiles are ceramic with a matte glaze-- easy to clean but not slippery. My wall tiles are 2x4 large format porcelain tiles in a polished finish. I considered marble, but the maintenance requirements were too high for me.

I am thinking to go with porcelain tile now!

I would do the same if I had it to do over!