[villagetinker]

I had a call (at my house) asking about Sno-Cap and stating that they would send a PM, it was apparent that I should not call back on the work number.

No contact after several dyas, so here is what I think they wanted:
Sno-Cap, available for ACE Hardware (probably others but I have not checked). This is a Powder, you mix with water, and using a garden sprayer spray of the irrigation water discolored areas. Let set for several minutes, and wash off. You can probably use a hose, I use my pressure sprayer. The stuff works really well, I have never needed a second application. I use this on the stucco, side walks, and pavers.
Hope this helps.