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Thread: High Chlorine! High CYA?

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    qbot's Avatar
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    High Chlorine! High CYA?

    Greetings.

    I'm waiting for my test kit (I got the Leslie's brand FAS-DPD kit) so I've been relying on my local pool shop. These are my levels:

    FC: 8
    TC: 8
    pH: 7.9
    TA: 140
    CH: 290
    CYA: 70

    I'm trying to do the BBB method but can't do a whole lot without my kit. Used the pool this weekend and dumped 2 jugs of bleach in after a bevy of three year-olds were in there. Otherwise, I haven't done much to my pool since I opened it.

    Is my CYA level too high? I'm trying to refrain from using tablets. I know my FC is too high but, according to the pool shop, it will dissipate on its own. True?

    Curious,
    qbot
    ~23,000 gal In-Ground Gunite Pool
    Pentair Whisperflo .5 HP Pump
    Pentair Clean & Clear Cartridge (4) Filter

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    Re: High Chlorine! High CYA?

    Actually, 8 is pretty much right on the money for a CYA of 70. But, yes, it will dissapate on it's own. I'd try to keep it between 6 and 8 with daily applications of bleach.

    Maybe take your pH down a bit. Otherwise, numbers look good.

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    Re: High Chlorine! High CYA?

    Your FC isn't really that high. According to the pool calculator, with a CYA of 70, it should never be below 5 and your target is 10. I'd say your FC is about right (never let it go below 5 with your CYA.)

    If you don't have a salt water chlorine generator, your CYA is a little high. It makes your shock level 20, which will take a lot of bleach if you ever need to shock. You may want to bring it down to 50 by draining some water, but it's manageable at that level if you want to leave it there.

    Your pH is high. I would suggest adding enough muratic acid to lower it to 7.6 or so.
    32x16 ft Grecian rectangular vinyl pool 8ft on deep end - 19000 gal. 18" Hayward S-240 sand filter. 250K BTU Pentair MasterTemp heater. Hayward 3/4 HP Super Pump.

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    Re: High Chlorine! High CYA?

    Your CYA is kinda high at 70. By changing out a little water, you can lower this number.

    Actually, your FC is perfect on target for a pool with a CYA of 70. See the Chlorine CYA chart in the link below to understand this relationship.

    pool-school/chlorine_cya_chart_shock

    Your pH needs to come down. You want that between 7.2 and 7.8. If you are having problems with it rising fairly quickly, you might consider lowering your TA some and see if that helps.

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    qbot's Avatar
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    Re: High Chlorine! High CYA?

    Thanks guys.

    The pool calculator says I should replace 29% of my water to lower the CYA to 50. Is this advisable?

    Also, based upon what I've read, I am going to refrain from using any more pucks and only use bleach. That should keep my CYA relatively stable, yes?
    ~23,000 gal In-Ground Gunite Pool
    Pentair Whisperflo .5 HP Pump
    Pentair Clean & Clear Cartridge (4) Filter

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    Re: High Chlorine! High CYA?

    I don't know... I think that 70 is managable. You could probably go either way.

    I think I would simulate the replacement. Get a bucket of your pool water, and replace 29% of the water with your fill water.

    Then run a complete set of numbers. See if you like what you see.

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