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Thread: We lose CL by percent or ppm?

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    Whatrymes's Avatar
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    We lose CL by percent or ppm?

    I remember reading a couple of posts stating that it was normal to lose half of our CL per day, another words, the higher our target ppm, the more CL we should lose in 24 hours. I've read others say that it is normal to lose so many ppm per day which would mean higher target ppm would make no difference.

    I'm now curious to know if the former is true because since I've raised my target ppm my consumption has increased. When I shot for 4 ppm I never lost more than 2-3 ppm a day. Now I've raised my target ppm to 6 and I've consistently lost 3-4 ppm per day.

    So my question is, is it normal to expect a higher CL loss per day if we have relatively higher target FC ppm per day?

    Everything seems perfect.

    FC = 6.5
    TC = ~.2
    pH = 7.6
    TA = 115
    CH = 250
    CYA = 45

    No visible algae, OCLT = near 0,
    . . . and sparklin' clear.
    15 X 30 X 3.6 Ester williams AGP
    10,800 gallons
    Haywood EC40C90 DE filter 1 HP pump
    TF-100 Test Kit

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    Mod Squad Bama Rambler's Avatar
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    Re: We lose CL by percent or ppm?

    What has happened is that you have outstripped your CYA. IOW, you've raised your FC above the recommended upper level for your CYA of 45. If you raise your CYA then you'd lose less FC if you kept it the same.
    Dave J. TFP Moderator
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    Whatrymes's Avatar
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    Re: We lose CL by percent or ppm?

    Quote Originally Posted by Bama Rambler
    What has happened is that you have outstripped your CYA. IOW, you've raised your FC above the recommended upper level for your CYA of 45. If you raise your CYA then you'd lose less FC if you kept it the same.
    That makes perfect sense, thank you, love that explanation.

    Could I get your opinion on that last question? I'm curious about that one.

    Thanks,
    Ed
    15 X 30 X 3.6 Ester williams AGP
    10,800 gallons
    Haywood EC40C90 DE filter 1 HP pump
    TF-100 Test Kit

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    JasonLion's Avatar
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    Re: We lose CL by percent or ppm?

    Assuming a fixed CYA level and the same amount of sunlight each day, you lose a fixed percentage of your starting FC level to sunlight over the course of a sunny day. The exact amount of sunlight varies and there is also a rather small amount of chlorine lost to sanitation that doesn't follow this rule, so it won't be exact. But by and large, you lose a percentage of your starting level.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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