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Thread: Very high combined chlorine

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    Very high combined chlorine

    Looking for some insight here, I have an ungrounded pool, approximately 25000 gallon, for almost two years now I have been struggling with insanely high combined chlorine levels, have a Taylor k2006 test kit, here are my readings from this evening
    FC 6ppm
    CC 18ppm
    pH 7.4
    Ta 70
    Ch 120
    It has a salt generator, and the pump runs 24 hours a day, was very green in the spring at opening, but has been clear for a few months now, gets lots of sun, solar cover has been off for two weeks straight water temp is 86 degrees. Any suggestions would be greatly appreciated, this is my first post on here. Thanks for reading.
    25k in ground vinyl liner, aquarite swg, sand filter

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    Re: Very high combined chlorine

    One important test result is missing: the CYA. Did you pass all 3 criteria, originally, when and if you performed a SLAM when you were green? Are you adding anything like algaecide?
    26' X 52" Intex Ultra Frame. Intex Sand Filter
    26' X 52 Intex Ultra Frame Install
    You can lead a horse to (clear) water, but you can't force him to swim in it!

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    Re: Very high combined chlorine

    Or using a non-chlorine shock?

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    Re: Very high combined chlorine

    Cya is at 70, and at start up I did slam the pool, but couldn't get the cc to drop any, the weekend I added 15lb of Oct out chlorine free shock, and it dropped the cc 2ppm

    - - - Updated - - -

    No algicides added as well

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    Re: Very high combined chlorine

    Chlorine free shock skews the cc readings.
    Use the Overnight Chlorine Loss Test test per the link to determine if you have an organics problem or if the cc is simply from the MPS shock.
    In ground extended Grecian, 22,000 gal, Hayward 220t sand filter, vinyl liner, dolphin m4 supreme.
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    Helpful Links:
    GET A TEST KIT Chlorine/CYA Chart How to SLAM About Metals & Stains

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    Re: Very high combined chlorine

    Thanks a lot for the info, will post the results of the test tomorrow

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    Re: Very high combined chlorine

    Fc dropped from 6 to 4 overnight

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    Re: Very high combined chlorine

    If you never passed an OCLT, and never had <=0.5 CC, you never finished the SLAM
    32K gallon Plaster - 1hp Hayward 2 speed Super Pump - Hayward S200 Sand Filter - TF100XL
    Test Kits - Pool Math - Chlorine/CYA/Target/Slam Chart

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    Re: Very high combined chlorine

    The SWG was off for the OCLT?
    26' X 52" Intex Ultra Frame. Intex Sand Filter
    26' X 52 Intex Ultra Frame Install
    You can lead a horse to (clear) water, but you can't force him to swim in it!

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    Re: Very high combined chlorine

    Hi BD. well since you lost 2 ppm overnight, I'm afraid what we call a SLAM is in order.

    Please read up on process in the link and post back with any questions. Just remember that your cc readings are skewed from the MPS, so go by your FC loss when you do the Overnight Chlorine Loss Test after slamming for a bit.
    In ground extended Grecian, 22,000 gal, Hayward 220t sand filter, vinyl liner, dolphin m4 supreme.
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    Helpful Links:
    GET A TEST KIT Chlorine/CYA Chart How to SLAM About Metals & Stains

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    Re: Very high combined chlorine

    So I started the slam Monday night, used a total of 25 gallons of liquid chlorine 12.5% still the highest reading of fc I could get was 10ppm, that was testing after 20, 40, and 60 minutes after adding chlorine. Cya was at 50. Water became very clear this morning, this evening I have dumped another 20 gal of 12.5% liquid chlorine in and still can barely read above 10ppm fc. Maybe I am testing wrong? The last dose I added 10 gal in one shot, still can't get above 10ppm, any suggestions?

    - - - Updated - - -

    Also,is the pH test accurate while performing a slam?

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    Re: Very high combined chlorine

    If your Fc is below 10 the PH should read accurately. Above that it may be skewed. When did you test your CYA?
    26' X 52" Intex Ultra Frame. Intex Sand Filter
    26' X 52 Intex Ultra Frame Install
    You can lead a horse to (clear) water, but you can't force him to swim in it!

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    Re: Very high combined chlorine

    When you bought the chlorine, was it stored outside in the sun? Is it now in the sun? See if you can find a 5-6 digit number stamped on one of the jugs.

    And as for PAGirls question: not only when did you last check CYA, but also was in sunny out?

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    Re: Very high combined chlorine

    Tested the cya last night before the first addition of chlorine, chlorine came from bulk tank stored in a van trailer at the local pool store

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    Only sun it saw was in the bed of my truck from the pool store to my house , 10 mi drive

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    Re: Very high combined chlorine

    Was it sunny out last night when you tested CYA?

    Sounds like the chlorine should be fresh. Hmmm. That's A LOT of chlorine that you have added. Did you ever add a non-chorine shock or any bromine-containing products?

    - - - Updated - - -

    What is your current CC?

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    Re: Very high combined chlorine

    Never mind. I read back in the thread and saw that you did add non-chlorine shock. That will raise your CC value. Something's not adding up here.

    - - - Updated - - -

    If you added 20 GALLONS of 12.5% tonight and still have an FC of under 10ppm, I think you need to tell us step-by-step how you are testing.

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    Re: Very high combined chlorine

    I have the Taylor k2006 kit, I take a sample from between the shallow end return and the skimmer add the 2 dippers of dpd powder let it dissolve for about 5 minutes then start counting the drops, 0.5ppm per drop, then when it suits my fancy I test the cc which continues to be high

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    Re: Very high combined chlorine

    20 gallons of 12.5% in 25,000 gallon pool is 100ppm

    Something is off
    15,000 gallon inground fiberglass pool with spa. 350lb Sand filter, 1.5 hp pump, and heater

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    Re: Very high combined chlorine

    Is it possible there is ammonia in the pool, pool was green when closed with a lot of leaves in it, was obviously green when opened this April, have fought with elevated cc's for three years

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    Re: Very high combined chlorine

    Okay. Let's swirl, not dissolve, and no more suiting your fancy on the CC portion. Hahaha!

    Follow these instructions next test-time and see what you get:
    Pool School - FAS-DPD Chlorine Test

    - - - Updated - - -

    p.s. If you had ammonia, you would register 0 CYA, not 50.

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