Is this calcium scale?

[RPSalty]

I have these build ups. If I address them promptly, they are soft and easily brush away. If I wait, they harden and require a stone rubbing. Some are pebble like, others are streaks. All no matter when I address them, they leave the surface smooth and white where the blemish was. They tend to return at the same spot.

My chemistry is within recommended parameters. Which chemistry should I adjust to stop theses formations?

 

[mknauss]

Read Plaster Installation and Maintenance - Further Reading and see if any of those issues are comparable to what you are seeing.

 

[RPSalty]

==========================================
Mrfypark
------------------------------------------
Build Type: Plaster
Volume: 15000 gallons
------------------------------------------
Latest Test Result Summary:
FC: 3.5 (18 hours ago)
CC: 0.0 (18 hours ago)
pH: 7.8 (18 hours ago)
TA: 80 (18 hours ago)
CH: 375 (18 hours ago)
CYA: 50 (18 hours ago)
SALT: 3000 (18 hours ago)
TEMPERATURE: 95° (18 hours ago)
CSI: 0.21 (18 hours ago)
==========================================
------------------------------------------
Test Results 08-13-2023 @ 04:01 PM
------------------------------------------
Free Chlorine: 3.5
Combined Chlorine: 0.0
pH: 7.8
Total Alkalinity: 80
Calcium Hardness: 375
CYA: 50
Salt: 3000
Temperature: 95°F
CSI: 0.21

 

[RPSalty]

Read Plaster Installation and Maintenance - Further Reading and see if any of those issues are comparable to what you are seeing.

Good read. I believe the issue closely resembles calcium nodules.

The resurfacing was done over marcite around 2012. There was concern about the prep work before the pebble was applied. I guess I'll just keep brushing it off. One 2"x2" area the plaster came off and the edges now grow.

Thanks for your guidance.