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Thread: I'd like to understand rust stains better.

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    I'd like to understand rust stains better.

    I know the obvious things that will rust a pool. Hardware left sitting in one. Anything steel or iron. But what about other kinds of popular outdoor chemicals or products, or even indoor ones that might get left outside? Are there any dissolved forms of metals that could somehow cause a localized rust stain?

    Any thoughts are appreciated.

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    gtemkin's Avatar
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    Re: I'd like to understand rust stains better.

    High iron content fill water is a form of dissolved metals that will cause rust stains.

    Edit: Possibly local conditions at a spots in pool could cause metal to plate out at those locations.
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: I'd like to understand rust stains better.

    Quote Originally Posted by gtemkin View Post
    High iron content fill water is a form of dissolved metals that will cause rust stains.
    Do they typically form in a certain pattern or shape?

    Are they pronounced individual spots of rust that stand out from the rest of the color of the pool, or is does that stain large areas of the pool all at once, (ie the typical iron staining)

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    Re: I'd like to understand rust stains better.

    Brillo or steel wool will cause iron stains. Metal dust from cutting iron or steel will cause rust stains. Some plant food and fertilizer contain iron. Some salt contains yellow prussiate of soda (sodium ferrocyanide), which is an iron compound.

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    Re: I'd like to understand rust stains better.

    Quote Originally Posted by JamesW View Post
    Brillo or steel wool will cause iron stains. Metal dust from cutting iron or steel will cause rust stains. Some plant food and fertilizer contain iron. Some salt contains yellow prussiate of soda (sodium ferrocyanide), which is an iron compound.
    I'm wondering if there's anything that can go into a pool invisibly as a liquid (for example if someone put a small steel nut in a bottle of sodium hypochlorite, which might have dissolved in the bottle?) and then end up leaving a small but well defined rust stain.

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    JasonLion's Avatar
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    Re: I'd like to understand rust stains better.

    No, not really. That same steel nut dropped directly onto the bottom of the pool would form a localized stain, but if it pre "dissolved" in a bottle of bleach it would not form local stains, but rather either do nothing or cause stains across much of the pool.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: I'd like to understand rust stains better.

    If this is a concrete pool, it couldbe from rebar or rebar tie wires.

    Can you post a picture?

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    Re: I'd like to understand rust stains better.

    I can't at the moment. But I think I've seen rebar rust coming through and that's usually pretty severe looking compared to rust from any other source, right?

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    JasonLion's Avatar
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    Re: I'd like to understand rust stains better.

    It varies, depending on how much concrete is between the water and the metal. When the metal is right at the limit of where it will have any effect the effect is quite small. If the metal is closer to the surface it has a more visible effect, increasing to very dramatic right at the surface.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: I'd like to understand rust stains better.

    Where the rebars intersect, wire ties secure the bars together. Sometimes the ties will stick up and create tiny rust spots.

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    Re: I'd like to understand rust stains better.

    If possible, a picture might help but I realize that taking pictures of stains can be challenging. Apart from that you might tell us where the stains are and what kind of pattern if any, you see. For instance if there is a area of your pool that does not have as much circulation you might see stains form there first. Steps are a real common first place. I have also seen stains form that appear to be the natural pattern of the pools circulation or lack thereof. Determining the origin of stains sometimes is obvious and other times is requires a lot of detective work. The more information you can provide the better. Is there just one? Did it appear over night or slowly appear? How large is it? Is it getting bigger?

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