Flamed Bluestone Coping Deteriorating In Salt Pool

[Oski]

I have a 4 year old in-ground plaster pool that has Flamed Bluestone Coping and uses the Jandy Aquapure system. Many of the Flamed Bluestone coping stones are deteriorating and flaking. The worst area is in shallow area but several of the stones around the pool show this distress. It started about two years ago and continues to get worse. Some people say it is the salt water but others who have the same coping and even flamed bluestone under salt water state there is no problem. Is it just bad stones that need to be replaced or is it the slat water? More importantly, does anyone have any ideas on how to solve the issues without replacing all of the coping? Thanks.