After 9 largely uneventful years with my pebble bottom pool (always thought it was Gemstone, but I find now it's generic materials from the original plasterer), it began to crack and buckle in spots. In a matter of few months it went from a few spots to 20-30 places. It's splitting here, bulging there, and sloughing off in chunks. It's predominantly on convex edges (steps), but not exclusively (inch deep gouge in side wall of spa by filter intake).

The original plasterer has offered to drain and patch the obvious spots.

I am concerned that this will cosmetically address the problem for the next 6-months until the warranty concludes (10-year on pebble), and leave me holding the bag on a full resurfacing next year. I've been threatened that's it clearly a water chemistry issue and that I had better have 9 years of chemistry data if I want to make it a warranty issue.

(a) Is there anyway to determine if this is truly a chemistry issue vs. materials/labor issue?

(b) is it usual practice to demand water data for 9 years if I've used licensed pool contractors straight through?

(c) any hope that a patch job will be sufficient or do I need to re-plaster & pebble from scratch?

Suggestions welcome as I'm getting the run around and exhausted from it.

Thanks!