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Thread: Free chlorine going down too fast

  1. Back To Top    #1

    Join Date
    May 2015

    Free chlorine going down too fast


    I was using Costco tablets and my CYA went to 100. So I was told here to switch to bottled bleach. I went to the math calculator and it said to replace 44% of the water to lower CYA which I did. Now my CYA is at 40, which I believe is good. Looking at the CYA to FC chart here I targeted my FC to 6.
    Problem it drops daily to levels like 3 or 4. I have to add bleach daily. Is it because I replaced 44% of the water?
    Note: I use generic bleach not major brands. I didn't add bleach today yet as I want to hear the experts opinions here first.

    My numbers:

    PH: 7.6
    FC: 0.5 (I didn't test in 3 days was too busy at work)

    Thanks a lot

    12' AG, 3200GA, cartridge filter, pool installed 6/20/2015, Taylor K-2006 test kit,

  2. Back To Top    #2

    Join Date
    Mar 2015

    Re: Free chlorine going down too fast

    I loose almost 3ppm FC daily with summer sun and CYA at 30. In Atlanta, you have worse sun than me. If your target is 6ppm, then you need to make sure your morning FC is at least 6ppm plus what you expect to loose for the day. If you are worried about your loss, then do the OCLT.

    Yes, you need to add bleach daily. If you want it simpler, then install a Stenner pump.
    29,000 gallon vinyl liner custom designed lagoon style in-ground pool (self-built 2015-2016), Hayward EcoStar VS pump, Hayward HP21404T Heat Pump (140K BTU), Hayward Pro Grid DE DE6020 Filter with Fiber Clear, Hayward Tiger Shark, 2 Hayward Color-Logic LED lights, Stenner 45MPHP10
    370 gallon Jacuzzi J-345 spa with ClearRay UV

  3. Back To Top    #3

    Join Date
    Jul 2014
    Hope Mills, NC

    Re: Free chlorine going down too fast

    Chlorine always needs replaced, its job is to kill organics by breaking down, and UV also breaks it down. If you only lose 2 to 3 ppm per day, you are doing it right.
    16 x 32 17500 gallons
    Vinyl in-ground
    Hayward 250# Sand Filter
    1 HP Pump
    Hayward SWG

  4. Back To Top    #4
    jtaves85mcss's Avatar
    Join Date
    May 2012
    Cincinnati, OH

    Re: Free chlorine going down too fast

    ^+1 to the remarks from Davejavu.

    Based on the CYA-FC chart, your minimum FC is 3 and target FC is 5 with CYA at 40. Losing 2 to 3ppm in a day with lots of sun is normal. You may want to adjust your target FC after additions up to 6 so that you don't fall below 3ppm during the day.

    I can go a few days without testing, but I do add chlorine every day. I know my normal daily usage and needed dosing amount to stay above minimum.

    As far as dosing today, I would take it up to 6ppm immediately and then test again at sundown and take it up to 10ppm overnight and do another test in the morning before sun gets on the pool - see
    Pool: IG 22k- 16x32 clipped corners- vinyl liner, w/ a great board. Built in 3/99, new to me 2/2011.
    Equip: Hayward 3600 DE filter, Hayward CL-200 Chlorinator (empty since 7/5/2013).
    K-2006 Test kit with Speedstir
    Located in Cincinnati, OH. TFP lurker since 9/2011, BBB interested since 5/2012 and converted 7/2013.

  5. Back To Top    #5
    Mod Squad tim5055's Avatar
    Join Date
    May 2014
    Franklin, NC

    Re: Free chlorine going down too fast

    I agree with others, feeding the pool,chlorine is a daily chore. That is why a lot of people automate the additions with a SWCG or a Stenner pump.
    TFP Moderator

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  6. Back To Top    #6

    Join Date
    May 2015

    Re: Free chlorine going down too fast

    Thank you everybody I m glad it's normal
    I will add daily



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