Should I use sequestering agent?

[Amir]

Thanks for the info. You basically want me use a mild acid? Last night I sprinkled some Cal Hypo (slow dissolving kind) on some of the areas and that seems to work. I will give the acid a try this week end and see if it helps any better.
Regards

Amir

[mbar]

If it comes up with the cal hypo then it is organic, and the chlorine will eventually remove them over time.