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Thread: Getting CYA under control

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    Join Date
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    Getting CYA under control

    So through my tests I have discovered that my CYA is 100+, all due to trichlor. I have turned off my chlorine feeder and removed the remainder of the trichlor tabs. I have dropped my pool water to an inch or two below the skimmer once and brought it back up in attempt to get CYA to good normal range. Couple questions

    When I retest the CYA, should I have the pump/filter running for a bit to mix the new and old water?
    How long should I wait after adding new water to test CYA?
    Is there any hope that I will be able to swim in my pool this weekend, or ever this summer?
    In-ground, vinyl pool, full sun - 23K gallon, Leslies (Hayward) pump, Hayward 60 sq ft (300 lb) sand filter

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    AnnaK's Avatar
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    Re: Getting CYA under control

    Quote Originally Posted by jtkopp
    When I retest the CYA, should I have the pump/filter running for a bit to mix the new and old water?
    Yes, I would run the pump for whatever is your normal amount of time before testing again. You would need to exchange 1/2 of the volume to get the CYA to 50 ppm. From what you're saying you didn't take out near that amount and might not see an appreciable difference when you next test.


    Quote Originally Posted by jtkopp
    How long should I wait after adding new water to test CYA?
    As long as it takes your pump to do one full circulation. You can help it along by moving the water around with a leaf net or a good brushing. Take the test water from the place in your pool that has the least amount of circulation and down about an arm's length.


    Quote Originally Posted by jtkopp
    Is there any hope that I will be able to swim in my pool this weekend, or ever this summer?

    Sure, if your water is otherwise clear and sanitized. What FC level are you maintaining? How does your water look? You'll likely need to do several of these drain-and-refill cycles to get the CYA down to a more reasonable level.
    AnnaK

    12,500 gal AGP, Hayward sand filter, Pentair 2-speed pump, timer.
    Please visit our Pool Issues pages for information about step weights, managing the solar cover, and PoolSkim.

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    Re: Getting CYA under control

    I probably did not drop out enough water, but I also did not run the filter between the refill and the test. So I just dropped the water again down to an inch below the skimmer, but this time I used my vacuum head to sink the vacuum hose to the bottom of the deep end and took water out of there (I don't have a bottom drain). So not sure if that helps to get rid of the "bad" water, but it's a shot.

    The water is cloudy from an attempt of Green To Clean, and I am working on that. I will add water and run filter over night, then work on getting the pH back up. I am determined to swim this weekend.

    I have been running FC around 5, not realizing that my CYA was high. I just discovered that. Before I dropped the water today, my pH was 7.2, FC was 2, TA was 120, CYA was 100. I will have accomplished 2 water drops in the course of 6 hours by the time I go to bed tonight.

    Any other CYA advice you can offer would be greatly appreciated. I have been reading a lot on this website and on PoolSchool.
    In-ground, vinyl pool, full sun - 23K gallon, Leslies (Hayward) pump, Hayward 60 sq ft (300 lb) sand filter

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    Butterfly's Avatar
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    Re: Getting CYA under control

    Where are you located?

    Does your pool get full sun?
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

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    Re: Getting CYA under control

    I am in Vienna, VA (Mid-Atlantic). Pool gets full sun all day.
    In-ground, vinyl pool, full sun - 23K gallon, Leslies (Hayward) pump, Hayward 60 sq ft (300 lb) sand filter

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    Butterfly's Avatar
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    Re: Getting CYA under control

    I assume you have been to Pool School and know the recommended levels for CYA are 30 to 50 for bleach/liquid chlorine.

    However, being in full sun, having a sand filter, & having stopped using trichlor, you could probably do okay even if you can just get it down to 60-ish.

    AnnaK gave good advice.

    Welcome to the forum
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  7. Back To Top    #7

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    Re: Getting CYA under control

    Lowering only a few inches at a time will be a long process. For example, the area of my pool is about 600 sq ft so lowering the level 4" is about 1500 gallons, or about 8%. It would take 6 rounds of that to replace around 40% of the original water.

    The exact numbers for your pool will be different obviously but you get the idea--if you replace a little bit at a time, you need to replace more total water. Sometimes there's no help for it, for example if you have a high groundwater level.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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