White flakes in water

[steveinaz]

Recently, starting about 3 weeks ago, I started noticing white tiny flakes in my pool water. When I grab some with my net, they breakup with fingernail pressure, and dissolve. What are these?

The pool clarity is very good, this is the pools 4th season. It's a SWCG pool, plaster/gunnite. Balance is:

FC=3-6ppm (typically)
CC=0
PH=7.6 (requires weekly 3 cups of Muriatic to maintain)
TA=180ppm
Calcium= 710ppm
CYA=60ppm

Note: we did clean tiles this spring, using a pool pumice type stone from Leslie pool.

Any help is greatly appreciated.