What is this?

[swimfam]

Any direction on these spots - sort of looks like mold to me. (background: water was in rather good condition, detected a leak, let it drain down and let the chems go, fixed the leak, re-filled, now just getting everything back in order - or trying). I haven't done the overnight cl consumption test but seem cl has been being consumed rather quickly - understandable. I'm guessing I should just bring it to shock level.

Also, are the rust stains cause for concern? I've heard it's due to re-bar...?

Thanks for your input!