Quote Originally Posted by nefretrameses View Post
It's really quartz crystals (i.e. sand) but is includes green and blue particles that are the same color as the "specks" in the finish. I
That pretty much narrows it down, to dissolved pool surface.

If you maintain your water, the rate of deterioration will slow, but won't immediately end. The reason is, aggressive water conditions penetrate into the finish, weakening the matrix that holds the quartz particles. Where the matrix dissolves completely, the particles are immediately released. But where the matrix is only weakened, it may be some time before those particles shed.

FWIW, I'm pretty sure some of those surfaces can be refinished merely by regrinding them -- if the remaining surface material is thick enough. Marin would probably be able to either confirm or correct this, and possibly point you in the direction to carry it out, if it's possible.