One thing I learned about epoxy grouting river rock: you want to make sure a line is left at the edge for caulk (color matched) to be put in right at the plane change, or you risk cracking at the seams (I've heard of regular tile breaking, rather than the epoxy grout breaking, but in our case, I guess the rocks were flexible enough that the epoxy grout cracked instead). It's a bit tricky aesthetics-wise, because there's no natural break as there would be with a row of tile--we're just cutting a teeny groutline-sized line in and we've made sure to color-match the caulk to the grout very carefully. The lack of natural break with the rocks is why mongo has shown that he puts a row of tile around the outer edge of the floor of a rock shower--it provides you with a clear place to do the caulk plane change. But if you've already got the rock down, and no ability to edgeit, just make sure that there's a groutline's worth of space left around the outside and that caulk is put in there, rather than grouting all the way up to the beginning of the vertical.

I have the same type of rock work and use a hard plastic sports bottle with a sports drink pop top and have poured on up to 100% acid on the rock work. With that concentration it takes off the calcium on the grout immediately. Foams a lot. Then I just splash water on it. I have to add acid to the pool regularly anyway since I have a salt system. This still doesn't take off the calcium buildup from the rock itself as easily. HOWEVER, I don't know if I am damaging my grout at this strength- I've only had to do it a couple times. Maybe someone knows if I should also go back over it with a baking soda mixture to neutralize it? Anyone know? ALSO, Please don't do this on my recommendation- I don't want to get sued either and I don't know what I am doing!

"He said it passed the flood test and when the new curb and pan were built a new slope was built into the new shower pan." Could be semantics...could be poor grammar...could be obfuscation, however: 1) ",,,it passed the flood test..." Well whoop-dee-doo. Does that simply mean that it didn't leak? It should also mean that the water drains quickly and cleanly, with no water puddles left on the membrane. 2) "...a new slope was built into the new shower pan." "Into the shower pan" versus "under the shower pan". Who knows. Different terminology, semantics, wordsmithing. Again, it could have been done correctly or this could just be careful language. However, the sloped mud preslope should have been installed on the flat subfloor. The membrane should have then been placed on the sloped preslope. This way, the membrane itself is sloped to the drain. That is a building code requirement. On top of the sloped membrane goes another layer of mud. The tile gets thinsetted to the second layer of mud. Most water retention problems in mud bases are due to the membrane being placed flat on the subfloor and single layer of sloped mud being installed on top of the flat membrane, with the tile going on top of that single layer of sloped mud. Again, that is a code violation. With regular use of the shower, any mud layer on top of the membrane will indeed always hold some moisture. But if the membrane is sloped as it should be, excessive moisture in the mud bed will follow the slope of the membrane to the drain and exit the mud bed via the secondary weep holes in the drain. If the membrane is flat on the floor, then the mud bed can become saturated with standing water. The excessive buildup of moisture can turn into a mess. Big question, find out if the membrane itself is sloped. Choose your wording carefully. If you ask "was the membrane itself sloped, because if you didn't slope it, that's a code violation and you'll have to rip it out and rebuild it at your cost" they may just answer "yes". If you ask "can you tell me how the shower base was built, from subfloor-to-tile", you may get a better answer. Maybe they did slope the membrane. Maybe they didn't. Regardless, good luck with it all.

If we all liked the same things, it would be a truly boring world. Do you mean you like the small smooth pebbles (rather than larger rocks or stones) -- because if so, you can use that look ... but perhaps not as a construction material. If you truly like the "river rock" or any other non-conventional look, then consider using that look to to decorate rather than to build. If you could find a decorative bowl you truly like, you could fill it with pebbles/rocks and place them in any room in your house -- even more than one room. Does your bath get sunlight? Does your yard get sunlight outside the bath window or elsewhere? The reason I ask about sunlight is that there is now a solar powered water pump that could be put in a bowl or birdbath in the yard ... with small smooth creek/river pebbles below and around it to help hold the solar water pump in place for a water feature for your sunlight room or patio or yard. Sometimes stores -- sometimes even the Dollar Tree-- will sell smooth pebbles for planters/pots and you may find some you like well enough to use for decorative purposes. https://www.google.com/search?q=Solar+water+pump+feature+for+fountain+bird+bath&client=firefox-b-1-d&source=lnms&tbm=isch&sa=X&ved=2ahUKEwj4xtjBtqjqAhUej3IEHdRSChEQ_AUoAnoECA8QBA&biw=1366&bih=654 https://www.google.com/search?q=smooth+pebbles+for+planters+or+water+features&client=firefox-b-1-d&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjF17Xzt6jqAhXlhHIEHa03A0kQ_AUoAnoECAsQBA&biw=1366&bih=654 Let us know what you decide -- do post after pics.