Mysterious stains suddenly showed up

Ugotabkdin

Member
May 12, 2016
16
Sacramento, CA
Pool Size
16850
Surface
Plaster
Chlorine
Liquid Chlorine
new stains showed up suddenly after a week or two of rain during which I didn’t stay up on brushing, etc. It’s old plaster that has a lot of other widespread brown stains, but I was hoping to avoid any further staining…

The new stains are these tiny brown stains. Like flecks or brown. See pics; this is only about the dark brown, very small well defined stains—not the discoloration you see around them. Only the dark flecks are new.

. I have shocked pool, scrubbed the stains, applied muriatic acid directly to them, applied ascorbic acid directly to them. Nothing changed the stains one bit. I’m stumped.

See pics. Any ideas?
 

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Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
2,916
Rancho Cucamonga, CA
Pool Size
18375
Surface
Plaster
Chlorine
Salt Water Generator
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CircuPool RJ-45
If ascorbic acid had no effect, you can rule out rust from a metallic object rolling around in the pool. Do you have any organic material falling into the pool from nearby trees? Look up tannin staining and see if it applies. Tannin oil is found in variety of trees. Maintaining an elevated level of FC should fade the stains over time.
 

Ugotabkdin

Member
May 12, 2016
16
Sacramento, CA
Pool Size
16850
Surface
Plaster
Chlorine
Liquid Chlorine
Yeah there has been lots of debris falling in pool. Not really in the one area where the stains are, so that’s a bit weird. But I will maintain extra FC and see how it does. I guess that’s a good outcome if correct…
 

Ugotabkdin

Member
May 12, 2016
16
Sacramento, CA
Pool Size
16850
Surface
Plaster
Chlorine
Liquid Chlorine
Yeah there has been lots of debris falling in pool. Not really in the one area where the stains are, so that’s a bit weird. But I will maintain extra FC and see how it does. I guess that’s a good outcome if correct…
Update on this. I’ve maintained high FC for weeks. No effect on these stains. Ugh. Any other ideas?
 

MikeStone

New member
Mar 6, 2022
1
claremont, california
new stains showed up suddenly after a week or two of rain during which I didn’t stay up on brushing, etc. It’s old plaster that has a lot of other widespread brown stains, but I was hoping to avoid any further staining…

The new stains are these tiny brown stains. Like flecks or brown. See pics; this is only about the dark brown, very small well defined stains—not the discoloration you see around them. Only the dark flecks are new.

. I have shocked pool, scrubbed the stains, applied muriatic acid directly to them, applied ascorbic acid directly to them. Nothing changed the stains one bit. I’m stumped.

See pics. Any ideas?
same problem...it's caused by contamination...the pebble (most likely) and/or the abalone shells have some metal in them...pool needs to be resurfaced otherwise they will never go away!...make sure all contaminants are removed from pebble (i think they use magnets to filter out all stones that have metal in them)...
 

Ugotabkdin

Member
May 12, 2016
16
Sacramento, CA
Pool Size
16850
Surface
Plaster
Chlorine
Liquid Chlorine
same problem...it's caused by contamination...the pebble (most likely) and/or the abalone shells have some metal in them...pool needs to be resurfaced otherwise they will never go away!...make sure all contaminants are removed from pebble (i think they use magnets to filter out all stones that have metal in them)...
I don’t have pebble. Regular plaster.

I checked to make sure it wasn’t iron. It definitely isn’t. My working theory is now that it is caused by bits of wisteria seed husks. Somehow embedded in a way I can’t scrub out. Maybe a long shot. But I will know more once I get in pool.

Otherwise I just can’t figure it out. They are all concentrated on the side closest to where the husk bits would find their way into pool.