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Thread: Should my CYA level have gone up overnight?

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    Should my CYA level have gone up overnight?

    I got my test kit yesterday and the CYA tested at 30 ppm. I am SLAMing the pool. The overnight FC loss test shows a loss of 1.5 ppm FC. I tested the CYA again to make sure what SHOCK FC level to use and it tested at 45-50 ppm. Is it user-error on my part or does CYA go up with SLAMing? Just wondering and going to use the new reading to SLAM the pool today I guess. Any thoughts?
    18,000 gallon IG vinyl
    Hayward S220T sand filter, replaced sand 2013
    Sta-Rite pump, 1HP?
    New liner, 5/12; pool built in 1981;

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    Mod Squad tim5055's Avatar
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    Re: Should my CYA level have gone up overnight?

    Have you added CYA recently? It can take a week for the addition to fully register on the CYA test.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Should my CYA level have gone up overnight?

    No, have not added any CYA. I thought I understood that value should stay the same. What am I missing?
    18,000 gallon IG vinyl
    Hayward S220T sand filter, replaced sand 2013
    Sta-Rite pump, 1HP?
    New liner, 5/12; pool built in 1981;

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    Mod Squad jblizzle's Avatar
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    Re: Should my CYA level have gone up overnight?

    How did you do the test? Lighting is very important.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Should my CYA level have gone up overnight?

    I did the test before sun was on the pool. I think it's because I added water to the pool yesterday evening. That would do wouldn't it?
    18,000 gallon IG vinyl
    Hayward S220T sand filter, replaced sand 2013
    Sta-Rite pump, 1HP?
    New liner, 5/12; pool built in 1981;

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    Mod Squad jblizzle's Avatar
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    Re: Should my CYA level have gone up overnight?

    Adding water would lower the CYA. You need to do test outside in bright indirect light with tube near your waist. Try to test at the same time of day.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Isaac-1's Avatar
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    Re: Should my CYA level have gone up overnight?

    Are you using liquid chlorine / bleach for the SLAM as we suggest, or are you perhaps using a stabilized powdered chlorine product that will also drive up your CYA?
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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    Re: Should my CYA level have gone up overnight?

    Used the Austin's liquid chlorine shock from BJ's. I guess it is user error on running the test. I'll have to try again.
    18,000 gallon IG vinyl
    Hayward S220T sand filter, replaced sand 2013
    Sta-Rite pump, 1HP?
    New liner, 5/12; pool built in 1981;

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    Isaac-1's Avatar
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    Re: Should my CYA level have gone up overnight?

    If you are unsure of your readings you can pour the sample back and forth from the view tube until you are confident, it is good after mixing for several minutes.

    Ike
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
    I use and endorse TFtestKits TF-100 from http://tftestkits.net
    ~Remember TFP counts on your donations to keep this site ad free~

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    Re: Should my CYA level have gone up overnight?

    Good to know. I will do that next time I test.
    18,000 gallon IG vinyl
    Hayward S220T sand filter, replaced sand 2013
    Sta-Rite pump, 1HP?
    New liner, 5/12; pool built in 1981;

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