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Thread: White Crystals in Pool

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    White Crystals in Pool

    I just had my opened last week and there are white crystals growing on every surface that was under water during the winter. The sides, the walls, ¬*and even the thermometer are coated with hard white crystals. The only surface that is still smooth is the step that was left out of the water when the pool was drained for the winter.¬*

    Here is some more info: ¬*it's a gunnite surface and a salt water pool. It was installed in the fall of 2010. We brushed it for 6 weeks or so then it was closed. We continued brushing it when it was opened in the spring of 2011 and for all of last year all surfaces were super smooth. We had it closed last fall by the pool company and opened by them as well.¬*

    The crystals don't come off when I brush them but I was able to scrape some off with my finger nails.¬*

    Here are the numbers:

    FC - 0 (zero!) (I just turned the SWG on today)
    CC - 0 (zero)
    Ph - 8.2 (I fought to keep it down all last year)
    TA - 120
    CH - 600-700! (the test sample never really turned a blue color. It was very faint)
    CYA - 55

    Salinity 2.4


    Does anyone have any idea what caused this and how to get rid of them?

    I haven't called the pool company yet because I just got back into town and discovered this last night.¬*

    Thanks!
    Bart
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

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    Re: White Crystals in Pool

    Not an expert but with high ph & ch level I would assume it is scaling, lowering the ph would be a good first step.
    DONE, 20 x 40, inground gunite, 30" raised bond beam with 3 12" sheer descents, 8' diving board, pentair 420 cartridge filter, vs-3050 pump, intellechlor ic-40, auto cvr, Tahoe blue pebble tech, 6ea 4' x 12.5' & 2ea 1' x 12.5' helicol solar panels, legend robotic cleaner.

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    JasonLion's Avatar
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    Re: White Crystals in Pool

    That sounds rather like calcium scaling, and your test results are strongly suggestive of calcium scaling. However, calcium scaling isn't usually described as crystals. Do the crystals look anything like the ones in this topic? That kind of crystal results from a combination of high calcium and high sulfate levels. Sulfates can come from a variety of places, most commonly dry acid.

    Regardless of what is happening, the first thing to do is to bring your PH down to around 7.2, as bobby1017 already suggested.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: White Crystals in Pool

    "Crystals" was probably the wrong word. It's more like bumps or roughness. It doesn't look like the photo in the linked thread. I took a water sample to my local pool store for testing and one of the guys said it was scale. The other guy didn't know what it was (which was slightly troubling!).

    Here are the pool store test results:

    Saturation Index - .9
    CYA - 40
    Total Cholrine - .5
    Free Chlor - .5
    pH - 8.2
    Total Alk - 135
    Total Alk adjusted - 123
    Total Hardness - 200

    Here's photo of the "crystals"/scale on the thermometer:

    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

  5. Back To Top    #5

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    Re: White Crystals in Pool

    Sorry the photo is not that great.

    Also, I forgot to metion that the polaris bag was full of this stuff after running a couple of hours.

    I lowered the pH to 7.2 with 3 gallons of acid.

    If it is scale, is there something I can get to help remove it? THe pool guy said they had to order some of the "scale remover" as they didn't have any in stock. Does that stuff work or is it just something to sell to people like me?!?!
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

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    JasonLion's Avatar
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    Re: White Crystals in Pool

    If the scale is new you can sometimes get it to come off by lowering the PH to around 7.0 to 7.2 and adding sequestrant. Other times, especially if it has been around for a while, you need to either do an acid wash or manually scrape it off.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: White Crystals in Pool

    Thanks Jason!

    Does the fact that the scale appeared this year (the second year of the pool's life) and didn't appear last year when we opened it suggest the pool company didn't put some inhibitor in during the closing?
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

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    divepool's Avatar
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    Re: White Crystals in Pool

    Calcium and ph too high will cause this over the winter.
    22x52 IG 56K gal 3.6' to 11.6' deep, TruTile w/Vinyl Liner IG pool w/ 12" wide safety ledge
    StaRite System 3 Cartridge filter 450sqft S8M450, Pentair IntelliFlo VF pump 3.2KW
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    Saint Charles, IL

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