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Thread: Need for CYA??

  1. Back To Top    #1

    Join Date
    May 2013
    Washington, Il

    Need for CYA??

    So I've already added enough CYA to up the amount to 10 (according to bottle directions) but it's still at 0. This is powder form. Regardless, all of my other readings have been in the right range for over 2 weeks straight (including CC below 0.5 and FC around 2-3) by adding about a gallon of bleach a day. WEather is still cool here in central IL. My question is this: if my pool is doing just fine without CYA at this point, why should I add any???
    40,000 gallons (20' x 40'); IG; vinyl liner
    sand filter
    BBB method for 2 full seasons
    tf100 test kit
    central Illinois

  2. Back To Top    #2
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Need for CYA??

    Well, the test starts at 30ppm, so not surprised you can not read a 10ppm level.

    As the sun get more intense, you will start to lose more and more FC. I would bump it up to a level that you can actually test.
    Jason, TFP Moderator
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  3. Back To Top    #3
    Mod Squad tim5055's Avatar
    Join Date
    May 2014
    Franklin, NC

    Re: Need for CYA??

    10 is too low to test. The test will only detect 30 and above.
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  4. Back To Top    #4
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Need for CYA??

    CYA levels below 20 often show up on the test as if they were zero.

    Also, it can take up to a week for granular CYA to dissolve and show up on the test.

    If CYA is too low you will loose most of your chlorine to sunlight each day, requiring more total chlorine to maintain a level. Of course you don't want CYA too high either.

    For a regular outdoor pool we recommend CYA be between 30 and 50.
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