Is this plaster colored or worn through?

[shellsingleton]

Here's a few pics of the plaster around my new-to-me pool. The surface (as far as I can reach, water's about 60*) is smooth, no rough edges on the transitions between colors. The pool is about 8 years old. I'm thinking colored plaster?

 

[LeeD]

It looks to me that this is a colored plaster. Or at least it was.. Perhaps a Tahoe Blue or Caribbean Blue, though it is hard to tell for sure.

 

[shellsingleton]

What would have caused it to lose it's color?
edit- I know that the CSI being out of range would affect the plaster. But which particular chemical component would have affected it most? Right now the CH is kinda low, around 200, and it was at 170 a couple weeks ago when I took over maintainance. Slowly raising it with CalHypo.
The PH was fine.

How long should plaster retain it's color?

Thanks.

 

[LeeD]

Plaster will fade from sunlight, which is normal.. This one looks like chemical problems.. Hard to tell from here, but low or high PH can cause major problems. Low PH will eat away at the plaster, which could have caused the pitting and uneven surface. It also looks like there is some scale, which would be from high TDS and/or High PH. Dark colored plaster can be very difficult to take care of. As a pool builder and designer, I try to steer people away from dark plaster because of this. I prefer a darker pebble style finish instead.