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Thread: How Long Does CYA Last?

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    ThinkPad's Avatar
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    How Long Does CYA Last?

    How long does the CYA say in the water? I would appreciate hearing about experiences you guys have had with the stabilizer and how often to increase it.

    I have my CYA about where I want it, because of trichlor tabs. I'm going to stop using them for now, but I'm wondering about how long it will be until they are needed again. I'm hoping at least a year.

    Thanks!
    Bobby (my pool)
    18,000 gallon in ground/white plaster
    Flotec pump/Aquatech MYB100 single cartridge filter - runs 6 hours/day in evening during summer

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    Re: How Long Does CYA Last?

    In theory indefinitely. However, often times people who close their pools find that the CYA has vanished over the winter....

    But it should last all season assuming you don't have to drain off lots of water. Since you have a cartridge filter I wouldn't expect you needing to drain off/waste water unless you get large amounts of rain.
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    Re: How Long Does CYA Last?

    That's great to hear, however; in Florida it just keeps raining and raining. Right now my water level is above my skimmer opening, and it just keeps going up. If it doesn't evaporate soon, a partial drain might be coming up. I think in the past it has evaporated, though. That will take some CYA out.
    Bobby (my pool)
    18,000 gallon in ground/white plaster
    Flotec pump/Aquatech MYB100 single cartridge filter - runs 6 hours/day in evening during summer

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    Re: How Long Does CYA Last?

    The Cya will not evaporate. It will go out with the water if you drain,but will stay if water evaporates.
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    Re: How Long Does CYA Last?

    As mrcarcrazy stated, CYA stays in your water. There are only two sources of CYA loss -

    1. Degradation due to oxidation from chlorine which is EXTREMELY slow (probably only a few ppm's all season long)

    2. Water loss due to back washing or draining

    So you did the right thing by stoping the pucks! It's very easy to add CYA, lowering it is hard.



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    Mod Squad tim5055's Avatar
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    Re: How Long Does CYA Last?

    Yup, in sunny Florida (I lived there for 32 years) the daily afternoon storms which require draining water will be your biggest CYA loss. But, even that will be fairly slow.

    You may be able to keep up by just using the tabs when you go away for a few days as that will add some of the CYA back.

    Log your tests and I'm sure you will be surprised how slowly it goes down. You have to drain "feet" of water to affect it usually.
    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: How Long Does CYA Last?

    Okay, good, it does not evaporate. That helps keep the CYA stable. I guess I'll have to conduct a test at the beginning of every season (or more). Sometimes in Florida the pool can even be used during the winter, lol.
    Bobby (my pool)
    18,000 gallon in ground/white plaster
    Flotec pump/Aquatech MYB100 single cartridge filter - runs 6 hours/day in evening during summer

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    Re: How Long Does CYA Last?

    Quote Originally Posted by ThinkPad View Post
    Okay, good, it does not evaporate. That helps keep the CYA stable. I guess I'll have to conduct a test at the beginning of every season (or more). Sometimes in Florida the pool can even be used during the winter, lol.
    Good plan. It's usually good to check the CYA value at startup, anytime there's a water volume change and at close down at the end of the season. Weekly testing is unnecessary.



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    ship of fools's Avatar
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    Re: How Long Does CYA Last?

    I lose all of my CYA every winter when i close.

    I close with 30 - 40 and open at 0.

    I have never had issues with ammonia.
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    Sometimes I Wish Cartridge Filters Could Backwash

    Speaking of raining, I just had another downpour!

    Bobby (my pool)
    18,000 gallon in ground/white plaster
    Flotec pump/Aquatech MYB100 single cartridge filter - runs 6 hours/day in evening during summer

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    Re: How Long Does CYA Last?

    wait so does rain add or diminish CYA?

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    Mod Squad jblizzle's Avatar
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    Re: How Long Does CYA Last?

    Neither. It will dilute the CYA that is in the pool and if you drain out water, you will then be draining out some of the CYA.
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    Re: How Long Does CYA Last?

    Quote Originally Posted by Tristan View Post
    wait so does rain add or diminish CYA?
    Yes, jblizzle is correct. To further explain, CYA is added to the water manually, and it will stay there until the water is drained. Obviously, if more water is added to the pool, it will be diluted and not be as effective.
    Bobby (my pool)
    18,000 gallon in ground/white plaster
    Flotec pump/Aquatech MYB100 single cartridge filter - runs 6 hours/day in evening during summer

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