Pool-spa replaster surface issue mystery


Bronze Supporter
Feb 12, 2019
Austin, TX
Short background - Pool & spa were replastered spring of last year (Wet Edge Primera Stone Tourmaline). Initial pool finish was 15 years old, spa was 11 years old. Both were in decent shape but beginning to show signs of age. Coincident with the replaster, I shifted from trichlor pucks to TFP methods (testing 1-2x per week; daily additions of MA, liquid bleach and baking soda to minimize fluctuations). Saturation index has been maintained in the range of -0.3 to +0.3, and usually 0 to +0.3. Brush once a week with a SS brush. Hairnets in the skimmers. Water has ALWAYS been crystal clear.

Starting last year we began to notice discoloration of the new finish. It has slowly progressed to the point we became alarmed this year. Testing with a trichlor puck and MA on a sponge didn't yield any answers. Iron tested as zero (Hach $80 kit). Pumice stone doesn't really do anything. Phosphates were 1000 but I've gotten them down to 750 a few days ago as I was thinking calcium phosphate. But yesterday I dropped the water level for better pictures and attempted to get a sample with a razor blade or exacto knife (no luck as the finish is hard as can be). I'm beginning to think this isn't a scale issue at all but something within the plaster.

Wet Edge and the local replaster company are currently stumped, as am I. Please take a look at the pictures and offer any thoughts you may have.



TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
@onBalance has written about plaster quality for years....looks suspiciously like excessive white spotting likely caused by too much calcium chloride accelerant used in the plaster mix. See this thread -