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Thread: High CYA

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    High CYA

    I am fairly new to owning a pool, this is our second summer. Last summer our pool was blue all summer, this year we can not get rid of a clear green pool color. I was told my pH is 7.0 and my CYA is 100. Is there a way to bring down my CYA without draining my pool? It is a 18000 gallon pool, white plaster. with a spa. If I do have to drain it how much do i need to drain? I need to find this out before i spend a lot of money in chemicals to yield no results. Thanks






    [Edit:split/renamed:Butterfly]
    Steve from Texas

    18000 gallon kidney shaped gunite pool with attached jacuzzi

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    Butterfly's Avatar
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    Re: High CYA

    Hi TexasSteve,

    Welcome to the forum

    Please post a full set of test numbers and let us know how they were taken (strips, pool store, kit-what type?)

    We also need all your pool and equipment info.

    If you will go to Pool School (top of the page under the sub-heading & link in my sig) and read the first couple of articles, you will see what we need for you to include in your post. Once we have this info, help will be on the way.

    Odds are you will probably need to do several partial drains/refills to lower the CYA, but we really do need more accurate info so that we will not be guessing

    Post back all info in this thread and members will be along to help you.

    Looks like we have another member from Texas!
    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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    JasonLion's Avatar
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    Re: High CYA

    Sadly the only practical way to lower CYA levels is to replace water.

    One of the challenges is that the common CYA test can read CYA levels above 100 as if they were 100, so it is difficult to be sure what your CYA level really is. The minimum change would be to bring CYA down to 80, though I strongly recommend bring CYA down further. If your CYA level really is 100, you can bring it down to 80 by replacing 20% of your water.

    While you are thinking about that, you should look into how your CYA level got to 100+ in the first place. Trichlor tablets/pucks/sticks and granular dichlor "shock" all add CYA to the pool. If you continue adding CYA to the pool you will need to continue replacing water on a regular basis.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: High CYA

    TexasSteve, you can dilute your water sample 50/50 with regular water and retest the cyanuric to get a more exact result. Just double the result. This will give you a better idea of exactly how much water you need to drain and refill.

    We also need to know all of your test results. Please also include iron and copper test results..

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    Re: High CYA

    Quote Originally Posted by PoolOwnerNumber9
    Please also include iron and copper test results..
    Good call PoolOwnerNumber9! I was thinking along the same lines!

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    Re: High CYA

    Hi everyone. This is mysecond post, the first one did not have a full set of numbers, so here we go.

    FC......0.......working on bringing it up
    pH......7.2
    TA.......100
    CYA......100
    CH........350
    TDS.......1400
    Phosphates......50

    I have a plaster pool that is 1800 gallons and kidney shaped. with an attached spa. I have been running my pump (1 1/2 hp) for about 10 hours a day for the past week. before that only about 5 hours a day. It has been 100 degrees in Texas for the past few weeks. My water is a vey clear green, I can see to the bottom of my pool even sitting in my living room. This is the first year we have not had a nice blue pool and I have run out of options so I am looking for advice. I have read that using bleech is a good alternative to bring up my FC and does not contribute to my CYA as much. I have used the pool tool and, if I read it correctly, I would need my FC at 13 with a CYA of 100. Not sure if this would help get my pool blue or not? Also not sure how the water will feel on my eyes if I have a FC of 13. I added 192 oz of bleech tonight and heading to the store tomorrow to get more if it helps bring my FC back up.

    Help me if you can....goal is a blue pool!!!
    Steve from Texas

    18000 gallon kidney shaped gunite pool with attached jacuzzi

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    Ohm_Boy's Avatar
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    Re: High CYA

    Well, according to the Chlorine vs CYA chart, at a CYA level of 100, you'd need to reach a shock level of 39. That can be pretty tough to reach and maintain, and may not be kind to your pool.
    I would seriously recommend replacing around 20-30% of your water to lower the CYA so that the chlorine treatment can me more manageable.

    The trick to beating an algae bloom is to elevate your chlorine to shock level, and maintain chlorine treatment to keep it there until you win, which would be when your FC reading will hold overnight, your CC is 0.5 or less, and your pool is sparkling.
    Then, you can allow your chlorine to drop to minimum recommendation for your CYA level.
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

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    Re: High CYA

    Hello, Steve; and welcome to the forum.
    01) I suspect that the clear green may be copper; so we will need copper and iron tests to be sure.
    02) Is there any source of copper that could be getting in your pool? Sources could be a heater with a copper heat exchanger or copper algaecide.
    03) How do you add chlorine?
    04) Did you mean 18,000 gallons or 1,800 as you posted?
    05) Are there any stains on the plaster? If yes, please describe.
    06) I'm thinking a complete drain and refill. Would there be any problems with doing that? A high water table could cause the pool to float if not handled properly.
    07) With a plaster pool it is very important to maintain a neutral to positive SI. Your low pH and carbonate alkalinity are not good for your pool.
    08) If you have metals, you have to be very careful or they will cause severe stains on your plaster.

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    JasonLion's Avatar
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    Re: High CYA

    Your CYA level is too high. You really need to bring your CYA level down below 100, preferably well below 100. With CYA as high as it is now it will be very difficult to fight off algae. The only practical way to lower your CYA level is to replace water. The standard CYA test will often read levels higher than 100 as 100, so it is difficult to say exactly how much water you will need to replace. I would try for a 40% replacement first and see where that gets you.

    The rest of your numbers look very good. Make sure that your PH doesn't go any lower than it is now. Ideally you want PH around 7.5 to 7.8. If you are using trichlor tablets you will will want to raise the PH now, if you are using bleach you can leave the PH alone for now and it will probably be fine.

    Lowering the CYA level and shocking till you can maintain a FC level should take care of everything. There is a remote chance that copper is involved, but I wouldn't worry about it until you are able to maintain an appropriate FC level.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: High CYA

    You gave a FC of 0, but could you also give us either the TC or CC?

    Also, what are you using for testing?
    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!

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    Re: High CYA

    I drained and refilled my pool CYA is not a problem anymore., thanks for everyone's help
    Steve from Texas

    18000 gallon kidney shaped gunite pool with attached jacuzzi

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    Re: High CYA

    Quote Originally Posted by TexasSteve
    I drained and refilled my pool CYA is not a problem anymore., thanks for everyone's help
    But the next step is to get your CYA, PH, TA, etc... to the correct levels to obtain balanced water. Then keep it that way. Learn what it takes to do that.
    Mona SE MN
    24' round 48" high AG
    Meteor Sand Filter
    1.5 HP pump

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    Re: High CYA

    I did!! Thanks All of them are within the range and i have been checking them every nigth and morning. I have become moredisciplined since draining the pool. I really appreciate this forum, it has helped a lot
    Steve from Texas

    18000 gallon kidney shaped gunite pool with attached jacuzzi

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    Butterfly's Avatar
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    Re: High CYA

    Congrats and thanks for the update!

    Could you give us a pic?
    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!

  15. Back To Top    #15

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    Re: High CYA

    Not a great picture. but it shows my water is finally BLUE again!! heavy winds explain the few leaves in the bottom. Took it this morning before heading to work
    Attached Images Attached Images
    Steve from Texas

    18000 gallon kidney shaped gunite pool with attached jacuzzi

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    Re: High CYA

    CONGRATULATIONS!!

    Thank you for posting not only the follow up but, also the pic
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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