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Thread: Brown staining

  1. Back To Top    #1

    Join Date
    Jan 2015

    Brown staining

    Water sample returned no minerals in pool water. Chlorine, TA,calcium and PH perfect. This pool was newly plastered about 6 months ago. I am seeing brown staining on all the walls and steps. This is an indoor pool. What could be causing this? It's just getting worse. I tried pouring muriatic acid on a step in the water and it reacted very quickly like a puff of smoke. Stain completely gone.

    Any ideas?

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Brown staining

    Welcome to TFP!

    Brown stains are often iron. You can confirm that yours are iron by placing a vitamin C tablet on one of the stained spots. If the stain lifts around the tablet it is an iron stain. When the iron is in stains, it is not in the water, so it is not surprising if your water tests as zero iron.

    The other possibility is calcium scale with something else in it causing the brown color. Evidence of this would show up in your test results if calcium scaling was happening. If the vitamin C doesn't work, please post a complete set of water test results.
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