Remove metal stains from a plaster in-ground pool

[PoolDoc]

Took me awhile, but I found the MSDS, and here's what your looking at:

Sulfamic acid 5329-14-6 20-40 not set not set
Oxalic acid 144-62-7 20-40 1 2
Polybasic organic acid secret 20-40 not set not set
This is a commercial product whose exact ratio of components may vary slightly.

I think it could work, applied directly to a stain. But, if you tossed it in your pool, I believe you'd make a mess. Calcium oxalate would tend to precipitate out, which could explain your cloudiness.

Were you supposed to put this stuff in the, or just on top of a stain? United Chemical used to sell stain spotting bags that were filled with oxalic acid, I believe.

Uh-h, wait found some interesting titbit from their website:

+ After treatment a reduction in pH and/or total alkalinity may occur. If adding a pH adjuster (sodium bicarbonate) then do so very, very slowly.
+ Raising the pH and/or total alkalinity too quickly can cause a cloudy pool as well as re-depositing the stain back on the pool surface
+ Be aware that high levels of chlorine will reduce the effectiveness of Multi-Stain Remover. Ideally, reduce the chlorine level to zero before using this product

Ok, it was supposed to be added to the water . . . at low pH, and ZERO chlorine. (I seem to recall that chlorine and sulfamic acid destroy each other.) Then you had to gradually raise the pH (probably so the filter could remove the calcium oxalate as it formed, and possibly the metals as well).

Sounds like a great recipe for replacing stains with algae.

No, thanks.

[ MSDS & Lochlor source page archived. 20110624 ]