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Thread: Are CYA measurements affected by the level of chlorine?

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    Are CYA measurements affected by the level of chlorine?

    Are CYA measurements affected by the level of chlorine over 3 ppm?

    If so how could one compensate for this effect?

    Thank you.
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

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    Re: Are CYA measurements affected by the level of chlorine?

    I'm not sure what your question is. If you mean will the accuracy of the CYA test be affected by chlorine levels over 3 ppm, then the answer is no. Has someone told you this is true?
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    Re: Are CYA measurements affected by the level of chlorine?

    The reason for asking is that while in the pool store I noticed that there were some CYA measurement tablets (I use liquid to measure) that stated that the Chlorine level should be 3 ppm or lower for an accurate measurement.

    Thank you for asking.
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

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    Re: Are CYA measurements affected by the level of chlorine?

    The only dependable method for measuring your CYA from a pool service standpoint is by using the turbidimetric test (liquid test). No amount of FC will interfere with the turbidimetric test. The only thing that I am aware of that has been known to interfere with the CYA test is cold water tempertures.

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    Re: Are CYA measurements affected by the level of chlorine?

    Thank you for the very quick reply, that is great news.

    Aloha.
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

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    Re: Are CYA measurements affected by the level of chlorine?

    Actually, I believe I read somewhere, maybe an article by John Wojtowicz, that the chlorine bound to CYA would not form the melamine-cyanurate complex that is what results in the turbidity in the CYA test. Usually, the FC level is too low to significantly effect the CYA test, but if one wants to play it safe, then one can add some thiosulfate (2 drops of R-0007 should be sufficient) to the pool water sample and mixing before adding the CYA reagent.

    It might be interesting for someone with a pool at high FC levels, perhaps from shocking, to do a CYA test both ways. With this high an FC level, probably 5 drops of thiosulfate might be needed.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: Are CYA measurements affected by the level of chlorine?

    Wow Chem Geek, that is great info, a touch of true genius using the Thiosulphate first.

    Thank you
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

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    Re: Are CYA measurements affected by the level of chlorine?

    Chem Geek,

    Ran this test today, as the FC is still high at 22.

    CYA without 2 drops of Thiosulphate was 30 (sorry forgot), CYA with 2 drops 32, in other words not a meaningful difference,

    Thought you might like to know as you were kind enough to investigate this for me.

    Thank you.
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

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    Re: Are CYA measurements affected by the level of chlorine?

    Thanks for the test (you didn't write the CYA without thiosulfate, but from your conclusion I presume it was also around 32).
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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