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Thread: TA, CH and CYA values dropping normal?

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    TA, CH and CYA values dropping normal?

    From 4/21:

    FC 0
    PH 7.5
    CC 0
    CH 725ppm
    TA 300
    CYA 58

    Yesterday:

    FC 2.5 (in the late afternoon)
    PH 7.5
    CC 0.5
    CH 580 (-145)
    TA 200 (-100)
    CYA 50 (-8)

    I mean, it's great! I am just curious how that happens without having to do a water exchange. I have been getting the FC up to 7 every night. Could that have an effect? I haven't added anything but bleach.

    Maybe I'll have normal values by next month at this rate.
    18500 gallon oval pool. Filter: Hayward cartridge filter. Model: C12002. Pump: Hayward 1 speed (I think) 1.5hp Max-Flo XL Pump. Model: C48D43AO4. TFT100 test kit.

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    Texas Splash's Avatar
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    Re: TA, CH and CYA values dropping normal?

    Good morning. The only thing that would explain such a reduction would be water exchange - possibly rain? Testing error or variation could come into play perhaps for the CYA, but that's a big difference for the CH and TA. Those don't usually fluctuate so much.

    On a side note, if you're losing close to 5 ppm or more of FC each day or overnight, you have something brewing in the water. You might want to consider doing an OCLT to confirm, but that's too much loss each day/evening. Hope that helps. Have a nice day.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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    Re: TA, CH and CYA values dropping normal?

    Quote Originally Posted by Texas Splash View Post
    Good morning. The only thing that would explain such a reduction would be water exchange - possibly rain? Testing error or variation could come into play perhaps for the CYA, but that's a big difference for the CH and TA. Those don't usually fluctuate so much.

    On a side note, if you're losing close to 5 ppm or more of FC each day or overnight, you have something brewing in the water. You might want to consider doing an OCLT to confirm, but that's too much loss each day/evening. Hope that helps. Have a nice day.
    Could have been tester error on the first test as it hasn't rained since then. I am more comfortable now with the kit, plus I ordered the spinner, so that makes it easier as well hehe.

    I lose about 2ppm of FC overnight, so I think that is still in the normal range. I'm keeping a log and we'll see how it goes.

    Thanks!
    18500 gallon oval pool. Filter: Hayward cartridge filter. Model: C12002. Pump: Hayward 1 speed (I think) 1.5hp Max-Flo XL Pump. Model: C48D43AO4. TFT100 test kit.

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    Texas Splash's Avatar
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    Re: TA, CH and CYA values dropping normal?

    Got the speed stir - outstanding! Amazing how nice a small accessory can help things along. But I have some bad news ....... you should not be losing 2 ppm of FC overnight. That would indicate organic matter that is thriving in your water (even if clear for now) and you need to do a "SLAM" via the link below in my sig. If you're sure about your FC testing and/or the OCLT you performed, then I would SLAM right away and follow everything you see on the SLAM page. If you have any questions, please let us know. You're welcome to do another OCLT tonight if you have any doubt as to any testing errors, but if you lose any more than 1 ppm overnight, that's too much.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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    Re: TA, CH and CYA values dropping normal?

    But I have some bad news ....... you should not be losing 2 ppm of FC overnight.
    I agree completely. It may be that Faust is saying he is losing 2 ppm in a 24 hour period??? Faust, which is correct?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: TA, CH and CYA values dropping normal?

    Yes, I test in the evening so basically a 24 hour period. I am going to do a real OCLT tomorrow night as I won't be able to do it tonight. I'll post the results. Thanks for the tip!
    18500 gallon oval pool. Filter: Hayward cartridge filter. Model: C12002. Pump: Hayward 1 speed (I think) 1.5hp Max-Flo XL Pump. Model: C48D43AO4. TFT100 test kit.

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    Re: TA, CH and CYA values dropping normal?

    So I just did the OCLT and I only lost 1 ppm last night. So nothing eating chlorine overnight. At least that's good news.
    18500 gallon oval pool. Filter: Hayward cartridge filter. Model: C12002. Pump: Hayward 1 speed (I think) 1.5hp Max-Flo XL Pump. Model: C48D43AO4. TFT100 test kit.

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    Texas Splash's Avatar
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    Re: TA, CH and CYA values dropping normal?

    Maintaining only a 1 ppm FC loss overnight is positive. So now you have to consider the other two factors of your water - clarity and CCs. You know you want to keep combined chlorine to less than .5, and the water should always be crystal clear down to the deep end. If either of those are not true, there's a problem. It's also very important to keep your FC within the target range for your CYA at all times, so always keep that in mind and refer to the Chlorine/CYA Chart (link below). If you have any questions, let us know.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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