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Thread: Low Chlorine

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    Low Chlorine

    Free Chlorine 0
    ph 7.5
    TA 90
    CYA 50
    Total Dissoloved Solids 1550
    Phosphates 75

    My water has been cloudy since the beginning of the season in May. We have pine trees close to our pool. I cannot keep chlorine in my pool. I recently had a bout with yellow algae which is visually cleared up after adding a strong algaecide. I followed up with 5 lbs of shock that had a stablizer and clarifier over the course of 2 days. Then my chlorine went back down by the next day. What are your thoughts on this? The pool company says to add 5 lbs of CYA.

    Thanks so much.
    IG plaster, 16K gallon, Pentair NSP-60 DE filter, 2HP pump, BBB, Polaris 360

  2. Back To Top    #2

    In the Industry

    Join Date
    Mar 2007
    Knippa, Texas
    Assuming you DON'T have an SWG, DO NOT add any more CYA. The amount you have is good but a little on the high side. Are these numbers from your own tests or a pool store? What about CC's?

    I'm not one of the experts on this board, but I have been hanging around a lot so I know a few things. Cloudy water can have any one or more of a number of causes. It could be dead algae, in which case you just need to filter it out. I believe it's Waterbear who's fond of saying a clarifier can clear your water in seven days while filtering may take a week.

    In the absence of other information, I'd say keep your FC level up, say 15-20, with bleach and run your filter 24/7 for a couple of days. . .

    My pool: INDOOR 13x27 rectangular fiberglass, built ~2001, BBB, TA-60 sand filter, Hayward two speed pump (1 hp/0.33 hp), 3/4 hp booster pump for solar heater
    Taylor K-2006 test

  3. Back To Top    #3
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD
    A CYA level of 50 is just fine. Raising it will make fighting the algae much more difficult.

    The key to beating algae once and for all, particuarly yellow algae, is to bring your free chlorine level up to shock level and hold it there for a day or two. This requires being able to acurately test high chlorine levels and being able to distinguish free chlorine from combined chlorine. You need test the FC level, add chlorine to bring it up to shock level, which is normally 15 (but could be as high as 30 for some kinds of algae) (at a CYA level of 50), and to repeat this process at least three times a day until your free chlorine level holds overnight and you don't have any more combined chlorine.
    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

  4. Back To Top    #4
    Welcome to TFP! There are some great links in my signature that will help you!

    8000 gallon 20' x 48" round vinyl frame pool, 12" sand filter (don't have the specs on the pump), TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

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