Give us some recent test results and some from previous tests.
Add your state to your location so it shows up over there <---- so we know what your climate is.
Take a look at this and see which ones most match yours, Diagnosing Pool Plaster Problems
Then we can figure out what it is and what can be done about it.
If TFP helped you or saved you money - Become a TFP Supporter! <--Click here
2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach