Hi everyone. We are ready to have our new construction in-ground shotcrete pool plastered. We live in coastal SoCal so freezing isn't an issue if that matters. A pool forensics specialist (who is also a degreed engineer) said that the most durable finish is the old school one that contained asbestos (the original 50+ year old pool in his backyard he says is still like new - no erosion at all). This, of course, has long been banned, so I asked him what would be as close to that level of durability. He told me to avoid marble dust at all costs because that's what gets eaten away. He recommends nothing but white quartz sand with white Portland cement, but so far, the plasterers I encountered are pushing the pricier aggregates. I have no problem with that except one thing: every single product they're pushing still has marble dust of some proportion. It almost makes me suspect that the industry has a built-in replastering requirement. I figure the plastering pros will slam on this, but can somebody give me actual TECHNICAL advice on why white quartz sand with white Portland cement will not work? Thank you in advance.