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Thread: My CYA went from 50 to 0 over the winter

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    My CYA went from 50 to 0 over the winter

    I started having an issue keeping the FC level up in the pool so ran the CYA test. Looks like my CYA is close to zero. Just stared getting some algae. Going through the shock process now.

    Question 1: Is this normal to loose CYA over the winter?

    Question 2: Does this indicate a leak? I have suspected a slight leak as I have very small air bubbles in the filter basket and have to add water every 4 days. But I have run many bucket tests and the amount of water I am losing is under 1/4 an inch over several days compared to the bucket. Leak detection companies do not guarantee they can find a leak unless it is 1/4" per day.
    Phoenix, AZ
    Unknown pool size -Diving pool

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    Mod Squad zea3's Avatar
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    Re: My CYA went from 50 to 0 over the winter

    You can go to a fish or pet store and get an ammonia testing kit to check and see if you have ammonia in the pool. If you do have ammonia you will continue the shock process until it is gone.

    There are some cases where the CYA dissapears over winter and the pool does not develop an ammonia problem but that is very rare.

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    Re: My CYA went from 50 to 0 over the winter

    In another thread, this link was posted for low cost CYA.
    http://www.dtydirect.com/ProductDesc.as ... onditioner
    12500 AGP 2HP Sand filter
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    Re: My CYA went from 50 to 0 over the winter

    It is important that you have a good test kit, such as the TF-100 to test for free and combined chlorine. If you can post a full set of chemistry results, then we can further assist you.

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    Re: My CYA went from 50 to 0 over the winter

    Thanks for the tips.

    Pool is an in-ground gunite, about 15k gallons with spa. Pebble finish bottom, 2 pentair intelliflo pumps (one for water features), 420 sq foot pentair cartridge filter, ozone, located in DFW.

    Test results from TF-100:
    FC = .5
    CC = 0
    TC = .5
    PH 7.5
    TA = 80
    CH = 270
    CYA close to 0
    Temp 70

    I plan to buy some stabilizer to get the CYA over 30, and begin shocking. Will also pick up an ammonia test kit.
    Phoenix, AZ
    Unknown pool size -Diving pool

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    JasonLion's Avatar
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    Re: My CYA went from 50 to 0 over the winter

    If you suspect ammonia and CYA vanishing over the winter, you should not add CYA until you have started shocking. We have seen a couple of cases where CYA continues disappearing into the spring. Also, with CYA at zero, it is most effective to add chlorine in the evening, so you aren't losing most of it to sunlight.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: My CYA went from 50 to 0 over the winter

    Once you begin adding chlorine, watch for CCs to develop, which would indicate the presence of ammonia.

    What is the output of the ozonator and how much time does it run per day?

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    Re: My CYA went from 50 to 0 over the winter

    Funny enough I live in DFW also, and have noticed over the last few weeks my pool has been eating chlorine like crazy, did a cya test today and it was also 0.. Although I had a big leak this winter and had to replace half the water in my pool so im sure that has a lot to do with it. No CC or signs of problems though, I just added some stabilizer and used a few pucks instead of my liquid chlorine.

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    Re: My CYA went from 50 to 0 over the winter

    Quote Originally Posted by Ryanh1801
    Funny enough I live in DFW also, and have noticed over the last few weeks my pool has been eating chlorine like crazy..., did a cya test today and it was also 0.. Although I had a big leak this winter and had to replace half the water in my pool so im sure that has a lot to do with it. No CC or signs of problems though, I just added some stabilizer and used a few pucks instead of my liquid chlorine.
    Here in DFW, we have had some warm temperatures that is raising pool water temperatures enough to where things are able to grow in pool water fairly quickly. Now is the time to really be vigilant in dialing in your chemicals right to avoid having the pool water go green.

    For what it is worth, I almost always have to add CYA in the spring. I haven't had it go to 0 yet but I have had it <20 ppm. CYA is one of the first things I tend to in the springtime.

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    Re: My CYA went from 50 to 0 over the winter

    Thanks for all the help. I think I have my issue under control. It took 3 days of shocking, adding chlorine each night. It has been cloudy so I think that helped keep the CL up. Overnight chlorine loss was zero last night and no CC's.

    I will continue monitoring closely for the next few days.

    Not sure how to measure ozone output. It is an eclipse 1 which runs 9 hours per day (when pump is on).
    Phoenix, AZ
    Unknown pool size -Diving pool

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