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Thread: Can high FC levels (During shock) bleach out the Taylor CYA test?

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    Can high FC levels (During shock) bleach out the Taylor CYA test?

    Hi everyone,

    I let my pool get away from me, and am in the process of SLAMing it

    My CYA level in my SWG pool has been pretty consistent at about 60ppm, but after adding CalHypo last night to bring FC to 35ppm I thought this morning let me just re-test the CYA level, to make sure I am bringing the FC to the correct target.

    Using the Taylor 2006 test kit, I was able to fill up the test container with the little black dot to the very top and it was clear as I have only seen it on the day I filled the pool with tap water, and this makes me wonder if high FC levels will bleach out the CYA test and if it can even be trusted?

    Else I'll need to add some CYA, or I am going to have a lot of problems maintaining the SLAM levels (This would also explain why my pool FC wasn't maintained)


    Best regards

  2. Back To Top    #2
    JasonLion's Avatar
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    Re: Can high FC levels (During shock) bleach out the Taylor CYA test?

    The CYA test should still work when FC is high.

    A good double check is to watch how the FC level falls through the day. With CYA around zero you should lose all, or nearly all, of your chlorine through the day. But with CYA around 60 you should lose less than 50% of your chlorine through the day. Of course active algae will make that check meaningless, as you will lose your chlorine to algae.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  3. Back To Top    #3

    Re: Can high FC levels (During shock) bleach out the Taylor CYA test?

    Hi Jason,

    Thanks - I'll keep an eye out, and start fresh tomorrow if there is a significant drop in FC. The algae is not so bad (From what I can see visually)

    I have been reading up on CYA conversion to ammonia and what else I could find, because I've always been of the assumption that CYA doesn't get lost other than by loosing water out of the pool somehow.

    CYA has been pretty constant for the last 12-14 months, I let it move from 40 to 60 by using trichlor pucks, and last time I checked it was about 2-3 months ago (Still at 60ppm) because it was so stable. Was very surprised to see a reading that looked significantly less than 30ppm (More like 0 based on how transparent the CYA test solution water was). Even pondering if the test drops are faulty or something


    Thanks again
    Kim

  4. Back To Top    #4

    Re: Can high FC levels (During shock) bleach out the Taylor CYA test?

    After more digging around in the forums on CYA degradation, I am trusting this mornings CYA test and accepting that something happened to gobble up the CYA. Whether it's bacterial, it just gradually vanished or something else that accelerated it I don't know, but I have added CYA to the pool now and will test again in a few more days and a week, while keeping the SLAM going.

    This thread was very interesting, especially mas985 observation about smoke and ash in the pool.
    http://www.troublefreepool.com/threa...28CYA%29/page2

    I live in a tropical climate close to equator, the pool is open all year, and we get sugar cane fires that can dump sizable amounts of ash and debris into the pool. Now the ash will raise the PH of the pool, and perhaps even to the point where CYA degradation happens rapidly as chemgeek speculates. Perhaps there is something else in the ash that catalyzes the CYA degradation?

    All speculation - I will try and be more vigilant with the CYA tests during cane fire season


    Best regards,
    Kim

  5. Back To Top    #5

    Re: Can high FC levels (During shock) bleach out the Taylor CYA test?

    The ash could have provided nutrients for the bacteria.
    20,000 gal in-ground plaster pool with sand filter. Replastered recently. Mostly adding bleach and acid. CYA was high when I took over.

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