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Thread: CYA Disappeared?

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    CYA Disappeared?

    Hi,

    I tested my CYA with a K-2006 kit 3 weeks ago and the reading was about 35. Since then, I shocked to get rid of an algae bloom and have started adding polyquat. In addition, the pool has received 3 inches of rain.

    I tested CYA again today, and the reading is -0-. I don't think a few inches of rain in a 30k gallon pool is enough to drop CYA to zero.

    The reagent is only two months old, though I did mistakenly leave it out in the sun on a hot day for an hour or two.

    Can my CYA really be zero, or do you think the sun damaged the reagent, or something else?

    Thank you for your thoughts.
    28k gallon in-ground vinyl. Sand filter. Hayward pump. Manual chlorination.

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    Mod Squad Bama Rambler's Avatar
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    Re: CYA Disappeared?

    I doubt that the reagent is bad from just a couple of hours in the sun. If it was 35 and you have had to drain some water it's probably below 20 and it's just not showing up on the test. I'd assume it's 20 and add enough to get to about 40 and see what that does. If it's lower than 20 you'll be back about where you were.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: CYA Disappeared?

    Thanks Dave. We didn't actually drain the pool -- just lost a few inches to evaporation which I imagine would have left the CYA in the pool.

    Good idea on adding enough to increase CYA by 20ppm and see what happens. Will try that.

    Thanks.
    28k gallon in-ground vinyl. Sand filter. Hayward pump. Manual chlorination.

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    Re: CYA Disappeared?

    One other quick question: with low CYA (10-20), would FC of 7.0 be too high for swimming? That's where we are right now and kids want to swim.

    Thanks.
    28k gallon in-ground vinyl. Sand filter. Hayward pump. Manual chlorination.

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    Join Date
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    Re: CYA Disappeared?

    Quote Originally Posted by poolman10
    One other quick question: with low CYA (10-20), would FC of 7.0 be too high for swimming? That's where we are right now and kids want to swim.

    Thanks.
    Like Bama says, it's unlikely that your CYA dropped that low so it's probably safe to assume it's around 20. Shock level for CYA at 20 ppm is 10. Anything under that is fine for swimming.
    Bill
    18'X4' 7600 Gal AG
    3/4 HP Pentair Pump
    Hayward S166T 100 lb sand filter

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    Re: CYA Disappeared?

    Thank you.
    28k gallon in-ground vinyl. Sand filter. Hayward pump. Manual chlorination.

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