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Thread: Dark gray stains on diamondbrite SWG pool

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    Dark gray stains on diamondbrite SWG pool

    Hello, we are new owners of a 4 yr old diamondbrite pool with areas of dark gray blotchy staining predominately in deep end. We had the pool acid-washed, but the stains remain although less in some areas. We have converted it to salt. Any suggestions on what the stains might be. We are also seeing a very light brown stain by the steps...this has developed in the last 6 weeks. The water is clear and the chemical tests are okay. Thanks for any help you might share
    fun in the sun

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD
    Welcome to TFP!

    A full set of test numbers would help. There are often clues in the numbers that you might not see.

    I'm not sure right off what gray stains might be. Two good tests that can help narrow it down are to put some crushed vitamin C tablets in a sock and run the stain lightly with the sock and see what happens. Then rub the stain lightly with a trichlor puck and see what happens. The results of that will give us a lot more information.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    grey staining is often caused by copper. Have you ever used any copper based algaecides? Do you have a heater with a copper heat exchanger? Have you ever had your water tested for metals?

    Blotchy color can also be a symptom of scale deposits. Please post a full set of test results so we can see what your water balance actually is.

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