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Thread: White sandy deposits

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    White sandy deposits

    hello everyone!
    Need some help with a new problem we are having. We have an above ground 18 foot round pool and a de hayward filter. We just had a new liner installed and refilled with fresh water this spring. For the last month or so we have been noticing white sandy deposits on the floor of the pool. When we asked at the pool store they told us it was most likely mustard algae. Our water is crystal clear otherwise and its in full sun so its been really warm this summer. We treated with shock and algaecide as instructed but now the problem is worse than ever. Im not even sure if it was ever algae. Today I sucked up the 'sand' with a turkey baster and put it into a cup. Looks like white granules that settle. Also, although we have been backwashing, it seems as soon as we put the filter back on the strong circulation makes all this stuff settle in the center. What is it? Anybody have any ideas??

    Thank you!!

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    Re: White sandy deposits

    First, welcome to TFP!

    Well that certainly doesn't sound like mustard algae. It sounds a lot like DE from your filter, are you positive that it isn't DE? Have you squeezed it between your fingers to see if it is hard like sand or soft and breaks apart?

    If this is your first time to TFP I should give you the heads up that we do things a bit differently than pool stores. When there are algae problems we don't suggest algaecides and one-time shocks. To get an idea of what we tend to do you should check out the Pool School. Here are a couple links you might want to take a look at when you get a chance:

    Pool School - ABCs of Pool Water Chemistry
    Pool School - What is TFPC?
    JD - 28' Round Above Ground Pool, 17,000 Gallons. Dual speed Jacuzzi pump with cartridge filter. Dual speed 1 HP pump, Hayward S210T sand filter
    Pool School - PoolMath - HIGHLY Recommended Test Kits

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    Re: White sandy deposits

    Hi Donldson! Thank you for your reply and for the links! We have had an above ground pool for 20+ years now and have relied solely on bleach as our chlorine and baking soda for our pH adjuster so I'm very happy to see I've come to the right place!! 😄 We turned to the pool store out of desperation and after hundreds if dollars wasted in chlorine powder and algaecides, I am officially done with them. I guess he first thing I need to do is invest in a complete test kit. We only test with a basic chlorine/pH tester. And I am not sure that this sediment is not DE. It feels grainy to me but there is no way that it could be sand. Is it possible to have an overage of DE that would be returning to the pool via the return inlet? Would it make sense to dismantle the filter and clean it totally of DE and start over? I know its not exactly east to do with a pool full of water but I am willing to try anything. Backwashing alone does not seem to be working unless we are just adding too much earth. ?! Thanks for your help!!

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    Re: White sandy deposits

    Welcome to the forum.

    It sounds like you have "captured" some of it and can roll it between your thumb and finger. If so, that eliminates ANY algae and gets back, I think, to sand or DE.

    You have pretty much eliminated sand so the identity seems to be DE. I can think of nothing else, either, so you may have to go to work and absolutely clean that filter. I am not a DE guy but several here are and there is an article in Pool
    School.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: White sandy deposits

    Well it sounds like TFPC would be a nice extension of your current pool care methods! A TF-100 or k-2006 would definitely help keep another desperate trip to the pool store so consider it a good investment. Algae is not grainy, as Dave said, so it almost has to be DE (even with my low opinion of pool stores I still can't believe they concluded it was mustard algae). There may be an issue with your filter, unfortunately I also do not have a DE filter so I won't be much help troubleshooting the filter. We will make sure to send out word for anybody who has DE filters to give you some ideas.
    JD - 28' Round Above Ground Pool, 17,000 Gallons. Dual speed Jacuzzi pump with cartridge filter. Dual speed 1 HP pump, Hayward S210T sand filter
    Pool School - PoolMath - HIGHLY Recommended Test Kits

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    Re: White sandy deposits

    When wet DE clumps like a paste, and when dry it is powdery like flour. It is possible it is getting blasted out and settling in a fine layer on the floor of the pool. Can you post a few pictures of your pool, filter, and the collected material? How long has it been since you opened up the filter and cleaned it out? Getting a good visual of the inside of the filter and all the elements can help determine if there is anything that needs repair. Also what brand is your filter and does it have a multiport valve, push/pull valve, or a bump mechanism?
    TFP Moderator
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    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
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    Re: White sandy deposits

    Add a half pound of de in the skimmer and watch the returns for 1 minute. If de is bypassing the filter, you will see it coming out of the returns.

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    Re: White sandy deposits

    Quote Originally Posted by JamesW View Post
    Add a half pound of de in the skimmer
    One valid interpretation of that suggestion is to just dump half a pound of dry DE powder in the skimmer. Is that what you meant to suggest ?
    23,000 gallons IG gunite, pebble (I think)
    Hayward SP2610X15 1.5 HP Pump, Hayward sand filter
    Mineral Springs SWCG (it's actually Hayward/Goldline), Hayward Goldline T-CELL-15
    Polaris pool cleaner (with booster pump)
    TF-100, SpeedStir, K-1766 Taylor Salt Test, Lamotte Borate test strips

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