White marks on Plaster

[sandjam]

My pool is about 2 years old (gray plaster)and recently I've noticed that there has been a lot of white marks appearing on the bottom> Some small and some quite large. In the deepest end there's a very large spot that looks like something was spilled(kind of like a big splash mark). Any Ideas? Right now im in the process to lower TA and PH


FC 2.5
CC .5
Tc 3.0
PH 8.2 (always has been on the high side)
TA 120
CH 550 (never really got it to turn a blue more purple)
CYA 40

 

[Guest]

based on your numbers I am going to guess that they are scale. If that is the normal water balance you have kept it's a sure recipe for scaling. I am going to assume that your TA has always been high in addition to your pH, as has your CH. High pH is the main factor that will determine scaling conditions! (and you stated that you've always had a problem keeping you pH down--this is linked to too high a TA.)

 

[sandjam]

So what can I do about the scaling?

 

[Guest]

So what can I do about the scaling?

If it's severe (and yours seems to be from your descripton), then acid washing is about the only thing.
To prevent it you need to get your water balanced.
Do these marks feel different than the rest of the pool surface?