Discolored PebbleTec

[CFWilliams]

Hi all - I wasn't exactly sure where to post this, but as I am still fairly new to pool ownership...this was my best guess:

I know it's hard to see, but is the discoloration on our pebbeTec finish cause for concern? I honestly don't know if it's been there since we moved here (4 mo) or if it's something that I'm doing to cause it. Our water wasn't this clear (this looks clear, right?) until recently so perhaps I'm just now noticing it? I'm planning to call the people who built the pool tomorrow to see if they can come take a look. I have used only liquid chlorine for the past month or so and muriatic acid to keep my (ever rising) pH at 7.6. Below are my most recent readings. Thanks in advance for any insight.

FC: 5.5 (added LC to get it up to 8 just now)
CC: 0
pH: 7.8
TA: 70
CH: 340
CYA: 60

 

[JoyfulNoise]

Crush up vitamin C tablets in a nylon or thin sock and rub it over a stained area for 5-10mins. If it lightens up or disappears then it's iron staining. If it doesn't go away or gets noticeably darker, it could be copper staining or calcium scaling that has captured dirt. If you have a trichlor tablet, you can rub that on it to see if it changes color. If it lightens up from the trichlor then it could be organic staining.

I wouldn't bother calling the pool builder as they will likely not give you much help or tell you to acid wash the plaster which is the last thing you want to do. If you can find out from the previous owner how they maintained the pool, it might help figure out the source of the problem.