Thousands of yellowish [grey poupon] colored spots

[jacthiele]

I have tried many things, but still not sure what I have with all these spots [size of nickels and dimes]. They started only in certain areas last fall, but now cover the entire pool bottom and up the walls about halfway.
1995 Gunite 15K gallon with shared Jacuzzi
FC=3 [Quit using 3" pucks and calcium hypo and Autopilot SWC since Sept 05]
TA=120
PH=7.5
Cal= 250
CYA= 0 and just recently at 25
Took ownership of this pool 1 year ago, and did not notice any spots. Past owner/s, via neighbor reports, let pool go due to divorces,etc. , so I assume some surface abuse occured.
Spots do not brush off, vitamin C does not remove them, pumice stone neither. [the occasional rust colored spot responds to pumice stone]
The finish appears slightly pitted/rougher at each spot.
Last year I tried copper to clear them, and got in some additional trouble with black stains when shocking with calcium hypo. The only time I ever saw them greatly reduced/almost gone was with a direct application of cal hypo directly on a shallow end patch about 2'x3' last fall. That trick does not seem to work now.
I did let calcium get down to 80ppm over the winter here in Atlanta,GA, and I am guessing I caused the spots to multiply from 25% of pool to 100%. I theorize either a hardcore algae is on them , or this is the color of my plaster after it loses its top finish.
I searched the forum for "yellow spots" and nothing came up, please anyone seen this before ?

[DavidD]

I've never seen it before however I have limited experience with gunite. You say these spots are "pitted". Do you think the top coat of the gunite is gone in these areas?

[jacthiele]

DavidD,

yes, I do suspect that the top coat is gone at each of these spots. I just dont know if I have algae growing in them, or that is the color below the top layer, or more important , what caused them all to happen.

I will submit a picture when I get my camera fixed.