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Thread: CYA and PH Reading

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    Wildcat's Avatar
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    CYA and PH Reading

    The forum as told me that with high CYA PH can read higher then it really is.Is there a correction factor that will allow me to gauge my true PH? I am working on my CYA but it is 125-130 and my PH measures at 7.5. What is it really?
    10000 Gal, IG Pebbletec, pop up cleaners,Hayward EcoStar VS, 425 sq ft Hayward Cartridge, waterfall feature

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    nedchavez's Avatar
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    Re: CYA and PH Reading

    High CYA will not affect your pH reading.
    High FC, above 10 ppm, will.
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    Jeetyet's Avatar
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    Re: CYA and PH Reading

    There is no "correction factor", sorry. If you want an accurate PH reading you'll have to let your chlorine level drop below 10. Thats assuming its above 10 now. If its not its too low for your CYA level and you're risking an algae outbreak.
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    Re: CYA and PH Reading

    Quote Originally Posted by Wildcat
    The forum as told me that with high CYA PH can read higher then it really is.Is there a correction factor that will allow me to gauge my true PH? I am working on my CYA but it is 125-130 and my PH measures at 7.5. What is it really?
    This forum told you high CYA will skew your pH? I must misunderstand you.

    Maybe you have this mixed up with high FC on the color block test.
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    Wildcat's Avatar
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    Re: CYA and PH Reading

    Sorry, I did mean FC. High CYA causes me to keep high FC thus skewing the PH results. My FC is in the 15-18 range with CYA about 125 so I have the Algae angle covered.
    10000 Gal, IG Pebbletec, pop up cleaners,Hayward EcoStar VS, 425 sq ft Hayward Cartridge, waterfall feature

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    Wildcat's Avatar
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    Re: CYA and PH Reading

    ph-at-high-fc-levels-t11428.html

    I should have done a search before asking my question. I actually understand most of the answer. But where is a chlorphenol color chart to be found? It seems to say that allows a reading even at high FC
    10000 Gal, IG Pebbletec, pop up cleaners,Hayward EcoStar VS, 425 sq ft Hayward Cartridge, waterfall feature

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    Re: CYA and PH Reading

    I have found that the pH reads accurately when the fc is below 15 percent of CYA and is read right away.

    What are your current pH and TA readings?

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    Wildcat's Avatar
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    Re: CYA and PH Reading

    Quote Originally Posted by JamesW
    I have found that the pH reads accurately when the fc is below 15 percent of CYA and is read right away.

    What are your current pH and TA readings?
    7.4 and 100
    10000 Gal, IG Pebbletec, pop up cleaners,Hayward EcoStar VS, 425 sq ft Hayward Cartridge, waterfall feature

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    Re: CYA and PH Reading

    Quote Originally Posted by Wildcat
    http://www.troublefreepool.com/ph-at-high-fc-levels-t11428.html
    I should have done a search before asking my question. I actually understand most of the answer. But where is a chlorphenol color chart to be found? It seems to say that allows a reading even at high FC
    For an FC below 20, using Taylor chemicals, you won't get an accurate reading by looking at a chlorphenol color chart. The thread you referenced from The Deep End explains this. All of the recommended test kits - Taylor's, Leslie's, and the TF-100 - use Taylor chemicals.

    The standard recommendation here is to lower CYA, for this reason as well as others.
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    Re: CYA and PH Reading

    Most likely the pH reading is correct. For your cya, you can maintain an fc of 9.5, which will help you obtain a more reliable ph reading.

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    Wildcat's Avatar
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    Re: CYA and PH Reading

    Quote Originally Posted by JamesW
    Most likely the pH reading is correct. For your cya, you can maintain an fc of 9.5, which will help you obtain a more reliable ph reading.
    I guess I thought it was best to maintain my target level than the minimum. I think target level fo rmy CYA of around 125 is 16. Maybe I'll let it drop to the minimum in order to check the PH and then bring it up some to be safe.

    Just my luck as i am trying to count on rain water to help my refill we have had lower than average rain this monsoon season. Less than 4 inches and we had around 10 last year.
    10000 Gal, IG Pebbletec, pop up cleaners,Hayward EcoStar VS, 425 sq ft Hayward Cartridge, waterfall feature

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    Re: CYA and PH Reading

    For your CYA, I would keep the FC in the 10 to 20 range, but as close to 10 ppm as possible without going under. A lot depends on how frequently you test and add more chlorine. 15 to 18 ppm is fine is that's what it takes to ensure that you never go below 10 ppm.

    Ideally, it would be best to get the CYA down to a better level.

    I think that your pH readings are probably accurate as long as you are mixing the sample and matching the color right away.

    The risk is that if the pH is reading a false high due to high chlorine, then the pH might be too low. However, based on the TA, I don't think that it is.

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    Wildcat's Avatar
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    Re: CYA and PH Reading

    Quote Originally Posted by JamesW
    For your CYA, I would keep the FC in the 10 to 20 range, but as close to 10 ppm as possible without going under.

    The risk is that if the pH is reading a false high due to high chlorine, then the pH might be too low. However, based on the TA, I don't think that it is.
    Yes, that is what I inferred also, that with my TA PH is probably about right.

    Another 100 degree day in Tucson. Looks like it could be a long pool season
    10000 Gal, IG Pebbletec, pop up cleaners,Hayward EcoStar VS, 425 sq ft Hayward Cartridge, waterfall feature

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