Hi, new to this forum and pool ownership so I am turning to this forum to get some guidance on a situation that is affecting my below ground pool. Recently I have noticed some gray spot on the bottom of the pool with a hard white/light gray elevated center which seems to be expanding, multiple spots throughout the pool. Some of about the size of a a half dollar and new buds are now forming throughout the pool. I was able to remove the precipitation with a steel brush leaving a smooth finish but the stain seems to be embedded into the pool's surface. I have treated the pool with Scaletec which has softened the precipitation but I have not notice any clearing of the gray stains and the gray buds seem to continue to appear.
I have a 14,000 pool with a saltwater chlorinator. Below are the results of my last water test:
Total Free Chlorine: 4ppm
PH: 8.0 (added acid to reduce the PH)
Total Alkalinity: 115ppm
Calcium Hardness: 315ppm
Stabilizer: 60ppm
Total Dissolved Solids: 3,900ppm
Salt: 2,800ppm

Any advice as to what could be the cause and how to remedy would be greatly appreciated. Would love to be able to get rid of the gray stains.