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Thread: One lone, distinct, metal stain

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    One lone, distinct, metal stain

    Just recently I had one very distinct brownish stain show up on my wall about 2 feet below the surface in the deep end. It's got a really dark center about the size of a quarter with 3 streaks about 3-6 inches long coming out of it. In the same area there are also a couple small dark blue/black lines. I tried the vitamin c tablet test and it definitely lightened the brownish streaks and made the central stain smaller - after about 15 minutes of rubbing. It did not appear to help the smaller blue/black marks. The next day the entire stain was back though. The only other possible sign of metal in the pool is that my pump strainer basket seems to be turning yellow. There also looks like some bluish streaks at the bottom of the pool under the primary stain.

    I've since started to lower my pH which tends to be high (7.8). I've also added some "Metal Control" and ordered some Jack's Magic Pink Stuff and 2lbs of Ascorbic Acid just in case an AA treatment is recommended.

    Is it odd to have just one stain that is so distinct? Does free metal in the water tend to deposit in just one place? It is near where an opposing return is directing flow. Is it possible there is metal leeching from the gunnite below the plaster? Perhaps from poorly covered rebar?

    Once I get the pH down to 7.2 and get some Magic Jack's Pink in the water, I plan on using dry acid directly on the stain to try to remove it. If that doesn't work, is an AA treatment advised?

    Location: Maryland
    Water Temp: 80
    FC: 2.0
    PH: 7.5
    ALK: 95
    CH: 160
    CYA: 40
    22K gal, PebbleSheen Aqua, 1.5 HP Jandy Stealth pump, 460ft cartridge filter, Polaris 360 robot

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    duraleigh's Avatar
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    Re: One lone, distinct, metal stain

    Welcome to the forum. A pic might help a lot. That sounds a bit unusual
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Richard320's Avatar
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    Re: One lone, distinct, metal stain

    Welcome!

    A picture would really help.

    I had rust freckled from something that got knocked in the pool when my fence was being replaced. I stuck a handful of Vitamin C in a sock with a few rocks for weight and left it on the stain overnight. Well, actually, a few days, since I got lazy.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: One lone, distinct, metal stain

    Sorry for not getting pictures originally!

    You can just see the small blue/black part of the stain just above the center of the main rust/brown stain.
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    22K gal, PebbleSheen Aqua, 1.5 HP Jandy Stealth pump, 460ft cartridge filter, Polaris 360 robot

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    Re: One lone, distinct, metal stain

    Update: I got in the pool today and examined more closely and there is definitely about a dime size hole in the plaster at the center of this stain! How is that possible? The pool is only 3 years old and the plaster otherwise looks great. I can't tell if it's just concrete in the bare spot or rebar. I suspect rebar was too close to the gunnite and has reacted with the plaster and worn it away. Has anybody else heard of that? Is it even possible? I called my pool builder just now and I'm waiting to hear back. Any advice would be great.
    22K gal, PebbleSheen Aqua, 1.5 HP Jandy Stealth pump, 460ft cartridge filter, Polaris 360 robot

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    Re: One lone, distinct, metal stain

    BT, my 3 year old pool did the same thing. The rebar had to be cut out and the wall patched and it was determined the rebar was too close to surface. The rust will grow quickly and the spot will multiply, so the sooner you can get it fixed, the better.

    I have new, little black spots that will soon become rust again.....Looks like we both have poorly constructed pools
    10 x 26 IG gunite/plaster
    7300 Gallons
    Hayward Tristar single speed 1 HP
    Hayward CF C4025
    Pool DOB 1/10

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    Re: One lone, distinct, metal stain

    Yeah - this is not a good problem to have. Everything is under warranty still so I should only have to pay for refilling the water and chemicals to rebalance afterwards. So far my builder hasn't been overly responsive though. Even if they do repair this one spot, it seems like something I'll have to keep worrying about.
    22K gal, PebbleSheen Aqua, 1.5 HP Jandy Stealth pump, 460ft cartridge filter, Polaris 360 robot

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    Re: One lone, distinct, metal stain

    I just want to confirm that Palmspriings is correct, that is definitely rebar rusting through to the plaster surface.

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    Re: One lone, distinct, metal stain

    My pool company inspected the stain yesterday and confirmed it is rebar. The guy also said "good thing you have a 3 year plaster warranty which will cover it". The pool has a lifetime (for original owner) warranty for the shell and plumbing. Seems like claiming this is a plaster problem is like going to the ER with a bone sticking out of your arm, and having them direct you to a dermatologist. I'm hoping I can get the pool company to agree any future issues will be covered beyond 3 years - we'll see how that goes. Since this is a result of their mistake, I also will hope they cover refilling the pool but I doubt that will happen.

    BTW - does anyone know if local building codes specify a minimum thickness of concrete over the rebar? If they do, how would I find what it is in my locality (Howard County Maryland)? Is there a trade organization that publishes some standard also?
    22K gal, PebbleSheen Aqua, 1.5 HP Jandy Stealth pump, 460ft cartridge filter, Polaris 360 robot

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    Re: One lone, distinct, metal stain

    Update: The pool company came out today and repaired the area and according to them it wasn't rebar - it was a small fragment of metal that likely got embedded in the concrete when the pool was shot. They said they see this problem occasionally. They said they chiseled out all the damaged/stained concrete (which was black) and went another inch or two into the clean concrete. They saved some of the concrete to show me, but said the metal was probably too small to remain intact. Unfortunately I wasn't home to inspect the hole before they patched it.

    Does this seem like a reasonable explanation? Is it common for some metal fragment to be introduced when the shell is shot?
    22K gal, PebbleSheen Aqua, 1.5 HP Jandy Stealth pump, 460ft cartridge filter, Polaris 360 robot

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    Re: One lone, distinct, metal stain

    My view is that it doesn't make a lot of difference whether it was rebar versus a piece of metal imbedded into the gunite. I suppose it could occasionally happen. If the pool guy did the job correctly, the rust staining won't return.

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