Plaster stains!! Metal oxidation, pollen, leafs, flowers... what's the cause?!


Bronze Supporter
Aug 10, 2017
I neglected to take care of the water chemistry for most of the winter. Being totally honest, I only checked/adjusted once between November and January. I did keep the pump running on the same normal schedule daily and kept running the dolphin multiple times a week. I picked up leafs and other debris once or twice a week. I brushed 2 or 3 times in the whole time, not much really. Anyway, there, that's my confession... :) In terms of color and visual cleanliness, the pool looked fine.

However, in February I got nervous enough about not having done much for so long and I tested the water and pretty much everything was off. So, I added Alkalinity Plus, Calcium, CYA, Muriatic Acid and Chlorine (not in that order!).

Those chemicals each got their respective aspects of the water corrected. Then I was gone for a week, and nobody did anything for the pool during that time. I came back and checked the pool. There were leafs and flowers (both from pear trees and live oaks) on the pool surface and bottom. And... There were stains! All the stains were brown but some had a greenish tint as well. Really, the darker ones look like a coffee drink spill, and the lighter ones like a kid's pee stain on a bedsheet. See photos.

I brushed them over with my poly-whatever bristles whale brush and the stains did not go away. I went and got a stainless steel bristles brush, brushed over them and the stains went away. I got the water tested and added muriatic acid and chlorine. Then, two days later, the stains were back! I got the water tested again, this time checking for metals and the pool store said I had "0.3" metal content (or was it IRON content?), and there were no signs of algae in the readings. So, I bought a bottle of Natural Chemistry Metal Free and applied it to the perimeter almost at midnight and ran the pump until the morning, I did not brush. When I checked the pool in the morning, the stains were mostly gone, though I could still see some very faint discoloration.

That application of the metal free was 3 days ago. So far the stains have not come back but the slight discoloration is still there. I have brushed over it with the normal brush, but it remains. I will have the water checked for metals again tomorrow. If the metal reading is still not at the lowest recommended concentration, then I am thinking of adding some more metal free...

Before adding the metal free, I thought it could be rust or may be pollen. Why rust? Because this is a saltwater pool. Why pollen? Because the flower of the live oak trees (see photo) and/or the flower of the pear tree stain my patio deck and have stained the pool leaft net too, and both with a brownish stain. (see photo). Anyway, now that the metal free seems to have addressed the stain, I am thinking it was metal, but where would it have come from?

Any advice? Suggestions? Theories?


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