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Thread: Low CH = hazy water?

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    Join Date
    Aug 2009
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    SF Bay Area (Lamorinda), CA
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    Low CH = hazy water?

    OK, I *think* I've got the algae under control (water is blue, overnight FC drop test was 0.5 ppm) but my water has a slightly white cloudiness to it instead of being clear.

    Test results last night:
    FC 11
    pH 7.4
    TA 110
    CH 90
    CYA 35

    I added the little Calcium Chloride I had left in the shed and that raised my CH to 120. Reading the book that came with my Taylor test kit, I see "Low calcium hardness: corrosive water - etching of plaster, pitting of concrete, dissolving of grout". We *do* have fairly soft water here, which is good for a lot of things but I guess not good for maintaining CH.

    Our pool is, according to the inspector/pool service guy who maintained it for the previous owner, a concrete/plaster one that for reasons unknown was re-lined with fiberglass by the previous owner. The fiberglass has been chipped in spots so there's some exposed concrete/plaster, and the grout *has* been pitted over the past few to several years (someday we *will* have enough $ set aside to have it resurfaced, sigh....).

    I'll be heading out to the pool store for more Calcium Chloride later this morning, but just curious as to whether the white haze sounds like just dead algae or if it's dissolved pool surface. Thanks!
    1950's-era 17K gallon formerly fiberglass, newly replastered IG rectangle (~15x30'),
    Hayward S244S Sand Filter with Franklin Electric 0.75 HP motor and WhisperFlo WFE-3 pump
    Clear ThermaTex bubble cover
    Manual vacuum

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    JasonLion's Avatar
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    May 2007
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    Re: Low CH = hazy water?

    The hazy water is almost certainly dead algae. Once the algae is all dead, it can still take a sand filter a week, or occasionally longer, to completely clear up the water.

    If there is exposed concrete/plaster you definitely want to raise your CH level to around 300. However, it might be best to wait to do that until your algae issue is completely cleared up. Otherwise the two procedures might interact to cause a little confusion about what is going on. Adding calcium can create some temporary cloudiness, and it is best to not get that mixed up with the cloudiness from the algae.
    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: Low CH = hazy water?

    so is my CH high enough to not cause any further damage while the algae clears up?
    Also in the past I've used alum to precipitate out the dead algae and vacuumed it out to waste to speed up the clearing-up process - is that a bad idea?
    1950's-era 17K gallon formerly fiberglass, newly replastered IG rectangle (~15x30'),
    Hayward S244S Sand Filter with Franklin Electric 0.75 HP motor and WhisperFlo WFE-3 pump
    Clear ThermaTex bubble cover
    Manual vacuum

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    37,879

    Re: Low CH = hazy water?

    You can use alum to speed things up if you want. We don't normally recommend it because it is a fair bit of work and doesn't always work, but you are familiar with how much work it is and can decide that for yourself.

    Low CH for a few days isn't an issue. It is low CH for months that causes problems.
    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

  5. Back To Top    #5

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    Re: Low CH = hazy water?

    Quote Originally Posted by JasonLion
    Low CH for a few days isn't an issue. It is low CH for months that causes problems.
    Looking back at my test results, it probably has been on the low side for a couple months - I see that on 6/24 it was 100 ppm, on 4/18/10 it was 120 ppm, on 11/21/09 it was 150 ppm. I admittedly haven't been testing the CH and TA as regularly as FC and pH so these are the most recent results prior to yesterday's and today's.
    1950's-era 17K gallon formerly fiberglass, newly replastered IG rectangle (~15x30'),
    Hayward S244S Sand Filter with Franklin Electric 0.75 HP motor and WhisperFlo WFE-3 pump
    Clear ThermaTex bubble cover
    Manual vacuum

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