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Thread: Vitamin C left two very very dark spots that don't brush off

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    Vitamin C left two very very dark spots that don't brush off

    Hello everyone,

    I have been reading the posts on this forum and learning a lot from it.

    Today I decided to do a test with vitamin C tablets on my pool that went very wrong. Here is what happened.

    My pool has a large area of a very dark stains developing over the years, so I decided to test with a couple of vitamin c tablets to find out if the ascorbic acid treatment would work for me. I went to CVS and bought a bottle of it, CVS brand, the description says vitamin C 1000 mg as ascorbic acid. They are non coated.

    I dropped two tablets in the pool and push them close together on top of a dark area. I waited for about 30 min and then I moved them. The result was two very very dark spots that would not brush off. I had to remove the spots with a Porpoise Rust Stone I had from Pinch a Penny a while back, but those things are very aggressive towards the diamond brite.

    What happened? Did anyone here have had this issue?

    Thanks,

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    JasonLion's Avatar
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    Re: Vitamin C left two very very dark spots that don't brush

    That means your stains are almost certainly copper stains. Vitamin C works wonders on iron stains, but it makes copper stains worse.

    The best treatment for copper stains is to never get them in the first place. They can be very difficult to remove, often requiring a full drain and manual acid wash.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Vitamin C left two very very dark spots that don't brush

    Thanks for your response.

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    Re: Vitamin C left two very very dark spots that don't brush

    It makes sense, since I do not have a metal latter and my water is from the city, however I have used copper based algaecides. I checked Jack's Magic web page and they mention something called Iron scale that is actually a copper stain caused by organic discoloration, and that makes the stain darker.
    This is most likely my problem then, because I started to notice the stain (much smaller) after hurricane Katrina left a ton of dirt in my pool that took me a while to clean.
    They recommend treating for scale.... do you think is worth to try before draining?

    Thanks,

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    Melt In The Sun's Avatar
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    Oct 2009
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    Re: Vitamin C left two very very dark spots that don't brush

    Just to clarify: iron stains, copper stains, and organic stains are all entirely independent of each other. Your stains are copper, as confirmed by the Vitamin C test and your use of copper based algaecides.

    Treating for scale could help if you have a lot of scale and the stains are embedded in it. The only long-term solution is to drain the pool, have it acid-washed, and refill with metal-free water.
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
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