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Thread: FC way high after adding CYA

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    FC way high after adding CYA

    I tested for the first time at home on 4/18 and got these results:

    FC - 6.8

    PH - 7.7
    TA - 90
    CH - 160
    CYA - messed this up but I know it was very low, if existent.

    Added half a bottle of acid then tested again on 4/22:

    FC - 7
    PH - 7.7
    TA - 110
    CYA - still low or at 0

    I had my "ah ha" moment after this test when I realized that the constant acid demand was due to 0 CYA. I added a gallon of liquid CYA around 4pm on 4/23 and ran the pump for 24 hours.

    Last night I tested again with some odd results:

    FC - 12

    PH - 7.7
    TA - 90
    CYA - 50 (finally clear on this test)

    Couple of qs. Is this even accurate or should I wait a few more days from the CYA add? Is the high FC from running the pump 24 hours? I know I still need more CYA, especially since I think it was at 0. Is it too soon to add the second gallon? Also is it ok to be in the pool with this high FC?
    17K IG Concrete w/hot tub; Hayward: Super Pump 125, Aqua Rite SWG, Navigator Pro, 250k btu heater, Taylor K2006

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    Texas Splash's Avatar
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    Re: FC way high after adding CYA

    Good morning Ashley. By using liquid stabilizer/conditioner, it should be fully recorded within 24 hours. The pump duration can indeed impact your FC production based on how you have things set there at home. Example: SWG designed to produce FC when the pump is running will continue to product FC, so you either have to reduce pump run times or reduce the percentage output on the SWG itself. That's something you have to play with. Pool School - Water Balance for SWGs

    Remember muriatic acid only effects pH and TA (lowers them). You might also want to consider raising your CH for the plaster since it appears to be low at 160. Whenever in doubt, please refer to the links below in my sig (Recommended Chemicals and Levels). Keep those handy. Let us know if you have any more questions.

    - - - Updated - - -

    Just to be clear .. when you say you "Added 1/2 bottle of acid", are you referring to muriatic acid (for pH) or cyanuric acid (CYA)? Something tells me now you're referring to the stabilizer/conditioner, but it's good be sure.

    - - - Updated - - -

    If your CYA is indeed 50, you can be in the water as long as the FC is below 20 (the SLAM level). And just to be safe, here's my CYA testing help quote:
    Proper lighting is important for the CYA test. You want to test for CYA outside on a sunny day, but keep the skinny view tube in the shade. Taylor recommends standing in the sun with your back to the sun and the view tube in the shade of your body. Use the mixing bottle to combine/gently mix the required amounts of pool water and R-0013 reagent, let sit for 30 seconds, then gently mix again. Then, while holding the skinny tube with the black dot at waist level, begin squirting the mixed solution into the skinny tube. Watch the black dot until it completely disappears. Once it disappears, record the CYA reading. After the first test, you can pour the mixed solution from the skinny view tube back to the mixing bottle, shake, and do the same test a second, third, or fourth time to instill consistency in your technique, become more comfortable with the testing, and validate the CYA reading.
    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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    Mod Squad kimkats's Avatar
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    Re: FC way high after adding CYA

    If you used liquid CYA (aka liquid gold LOL) the results are good as soon as the pump has run for about 30 mins to mix it in good.

    Ashley what are you using to test with?

    Here are a couple of links to help you out:

    Pool School - Recommended Levels

    http://www.troublefreepool.com/calc.html

    The pool math one may take some playing around with to learn but once you do you will LOVE it!

    A pool is safe to swim in so long as the FC is just a bit below the SLAM level. Here is that chart:

    Pool School - Chlorine / CYA Chart

    As you can see from this chart your pool IS safe to swim in with your numbers. CANNON BALL!

    PH does not test true when the FC is over 10.

    SWG works when the pump runs so that would explain why your FC is a little high. You will learn your pump run time needed as you test daily and see what your pool likes.

    Keep testing and asking questions! After a while you will know what your pool needs just by looking at it!

    Kim (must start looking to see if Pat is on the board before I post LOL)
    Last edited by kimkats; 04-28-2016 at 07:14 AM. Reason: Cross posting with Pat
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: FC way high after adding CYA

    thanks as always for the quick replies.
    When I said acid, I meant muriatic acid. So within the last 2 weeks, i have added a gallon of muriatic and a gallon of liquid CYA. I'm going to add the 2nd gallon of CYA today and then I should run the pump again for 24 hours correct? Then tomorrow I will start with a lower pump time. (Right now its on 8 hrs).
    I use the Taylor K 2006 and have the separate salt drop test.
    17K IG Concrete w/hot tub; Hayward: Super Pump 125, Aqua Rite SWG, Navigator Pro, 250k btu heater, Taylor K2006

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    Texas Splash's Avatar
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    Re: FC way high after adding CYA

    Thanks for clarifying. So it sounds like you're going through a fair amount of (muriatic) acid. Refresh my memory ... is your plaster new? Do you have much aeration (fountains, waterfall, spa spillway)? It's good you are controlling the pH (and TA) with the acid. As for the liquid stabilizer/conditioner, pour it in, let it mix for a while and check. Liquid registers faster than the granule type, but I would still give it some time to fully register so that you don't over-shoot your target. You have great test kits, so keep up the great work with those.
    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: FC way high after adding CYA

    " I had my "ah ha" moment after this test when I realized that the constant acid demand was due to 0 CYA"

    those things are not related. if your pH keeps rising, it is because you have curing plaster, good aeration, high TA, or some combo of all three.

    0 CYA would give you high chlorine demand, because the sun would be burning through it quickly during the day.
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    Re: FC way high after adding CYA

    Make sure you use the pool math calculator to ensure you don't overshoot your CYA target. I believe they recommend 70 for an SWG. (Be sure to choose liquid as the type in the calculator, if that's what you buy.)
    26' X 52" Intex Ultra Frame. Intex Sand Filter
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    Re: FC way high after adding CYA

    Chris - I'm confused again..the SWG page says low CYA causes high acid demand. Is this not correct? Thought I had it and I lost it.... I know my FC is much higher now that it's being protected by the CYA. The plaster is not new but I do have higher TA 90, and there is a little waterfall from spa to pool.
    Do I need to run the pump again for 24 hrs after the liquid CYA is added?
    17K IG Concrete w/hot tub; Hayward: Super Pump 125, Aqua Rite SWG, Navigator Pro, 250k btu heater, Taylor K2006

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    Re: FC way high after adding CYA

    Ashely, you must be referring to this:
    Second adjust CYA to between 70 and 80. The biggest mistake that many SWG owners make is NOT having enough CYA in the water! This can create a lot of problems like high acid demand, algae outbreaks, cloudy water, or early cell failure.
    There was decent discussion about it HERE, primarily because CYA serves as a buffer to other products.
    But generally for most pools, we relate the use of stabilizer and CYA level to FC protection from the sun and protecting swimmers/pool equipment from the chlorine itself.

    As for the pump Ashely, you don't have to run it 24 hours after adding the liquid stabilizer. Only because that stuff tends to be quite gooey and think, I would let it mix for a good 2-3 hours perhaps. Certainly if you added it today, by tomorrow you should have your new CYA reading.

    If your pH continues to rise quickly over the next couple weeks, I would suggest lowering your TA to about 70. See if that reduces the pH rise. You can even go lower to about 50-60 if you had to. Let us know if you have any more questions at all. Glad to help.
    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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