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Thread: CYA, CH down. What happened?

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    Join Date
    Sep 2016
    Location
    Tucson, AZ
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    7

    CYA, CH down. What happened?

    I've experienced an interesting anomaly over the past few months. Back in April I did the complete measurement suite and found that my CH had plummeted to near baseline, and CYA had plummeted to <30 compared to the previous measurements in February. I immediately suspected a leak to the pool or plumbing and so shut off the auto-filler to begin diagnosing the problem (using the bucket test to measure evaporation).

    No discernible leak.

    Has anyone seen this before? Any speculation on what might have happened?

    TIA for any and all ideas.

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    Richard320's Avatar
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    Jan 2010
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    San Dimas, CA (LA County)
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    Re: CYA, CH down. What happened?

    Speculation, yes.

    CYA will break down a few PPM per month naturally. Faster if certain bacteria get in the pool and chlorine levels aren't high enough to kill it and it starts eating it.

    If the water isn't leaking out and being replenished, then the CH is still there -- most likely as scale on the walls. Do you see any greyish- tan patches? Feel any roughness?
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    Re: CYA, CH down. What happened?

    You may be right, Richard. At this point all I can do it monitor it. If it turns out to be something else I'll report back to the group.

  4. Back To Top    #4

    Join Date
    Sep 2016
    Location
    Tucson, AZ
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    7

    Re: CYA, CH down. What happened?

    Update. Turned out to be a broken autofill valve. I'd noticed the water levels were high for a few months but thought it was due to rain. The water was leaking out at the top of the tile (between it and the apron). Replaced the autofill valve and everything is back to normal.

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