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Thread: Sand-Looking Stains in My Pebbletec

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    Join Date
    Apr 2016
    Springtown, Texas

    Sand-Looking Stains in My Pebbletec

    I've had my pool now for 4 years. We had a warmer than usual winter, and I did not maintain chemical levels as maybe I should have. Because I had black algae that developed, I super-shocked my pool with the initial application of 5 gals. of chlorine, and applied 1 gal. per day for 3 days, subsequently. I got rid of the black algae, but I have these sand colored stains that are appearing on my pebbletec. It's random, but it appears more in the more shallow areas of the pool.

    It is a salt system pool, and I have a DE filtering system if that is of any help. Also, the pool is 25,000 gals in size, and is a 3' to 5' to 4' deep pool.

    Any advice would be welcome.



  2. Back To Top    #2
    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    DFW, TX

    Re: Sand-Looking Stains in My Pebbletec

    Welcome to TFP!

    There's a pretty good chance that it is calcium scale.

    More here, Diagnosing Pool Plaster Problems
    And here, Pool School - Calcium Scaling
    TFP Moderator
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    Swampwoman's Avatar
    Join Date
    Apr 2012
    Grand Rapids, MI

    Re: Sand-Looking Stains in My Pebbletec

    Welome, Teedoff.
    One thing about stain management that is tricky is the ability to really definitively know your water parameters -- so any of my suggestions here rely on your having a home FAS-Dpd test kit (TFT100 or Taylor k2006, both available at ) the TFT water balance/sanitation method is dependent on knowing your cya:FC ratio (see link in my signature.)

    With that said, an easy test of the stain is to crush up some vitamin c in a small sock and hold it or place or set on stain for a few minutes. If the stain lightens, it is likely at least in part a metal stain.

    If it is metal, and you're not on well water, it is possible that the algaecide you used as copper in it that was then oxidized when you shocked/slammed. If you're on well or your municipal source as iron, it could alternately be that, which only became evident in a high chlorine condition.

    When you slam/shock, you are also breaking down any metal sequestrant that you have in the water (if you use same) and would need to re-apply.

    The more you can tell us about your water makeup source, what types of algaecide you've used, and how the staining reacts to vitamin c, plus a full water parameter report, the better the chance we can assist you, not only in preventing/ managing stains, but also in avoiding algae in the first place

    For example, if its scale, you'll need to manage your csi (see pool calculator). If its metal, sequestrant may help lift it, or alternately, an Ascorbic acid treatment plus sequestrant might be in order -- but sometimes if copper, a different formulation of stain treatment works better. (I personally would not try a stain removal process without a drop kit.)

    Controlling your ph and keeping it a bit lower, eg. 7.2-7.4, also helps reduce metal staining.

    Maybe we can help narrow down best options with more info
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  4. Back To Top    #4

    Join Date
    Apr 2016
    Springtown, Texas

    Re: Sand-Looking Stains in My Pebbletec

    Thank you!! We're not on well water, but it is a CO-OP, so the water source is a local lake. Nevertheless, I will either get my water tested or procure the kit and test it myself to get the answers to the questions you posed.

    Thanks again.


  5. Back To Top    #5
    Mod Squad kimkats's Avatar
    Join Date
    Jul 2012
    Tallahassee, FL

    Re: Sand-Looking Stains in My Pebbletec

    I will tell you that it is a sad thing BUT most pool stores (PS) do not do the tests the correct way I know you think they would BUT they are in the business of selling stuff so.......The more off they say your water is the more they can sell you.

    Here on TFP we do not sell anything. All we get for helping someone is a smile and thanks!

    There are two test kits we use. Only these two have the full set of tests needed to really balance pool water. There are others but they do not have all of the tests like these two: Taylor K2006 and TF-100. They use the same stuff but the TF-100 is sent with more of the stuff you use on a daily bases so it is the best bang for the buck. You can buy them from the link below in my siggy or amazon.

    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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