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Thread: FC and CYA

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    FC and CYA

    I was really freaked out about my high chlorine levels until finding this site! My pool is 18 ft in diameter and 4 ft deep - Vinyl.
    I have a FC of 10 and my CYA is 135.My ph is high ( 8 ) and after reading a bit on this site I am assuming I need to lower the ph, but that FC is fine due to elevated CYA. .... Yes??? The TA is 150.
    Up until about a week ago I was using chlorine tabs in one of those floating chlorine dispensers. I removed them last week due to the FC levels I have.
    Again .. to make sure I am understanding .... with CYA levels high I do not want to continue using the chlorine tabs but instead use bleach. Is this correct?
    How do I know how much bleach to add to maintain chlorine levels for optimum sanitation?

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    Mod Squad woodyp's Avatar
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    Re: FC and CYA

    Your Ph is high and you should drop it to mid 7 range or to 7.2 to help lower TA a bit which is also high but you can't lower that in one shot. Bleach has no cya in it and your cya level is already about twice as high as we recommend. Seriously consider draining some water to lower it. Poolmath in the tab at the top of the page will calclulate all your additions for you based on your gallon size. Welcome to the forum.
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    Casey's Avatar
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    Re: FC and CYA

    You definitely need to consider a drain/refill as your CYA is really high.
    I'd bet you my bikini you'll never get TFP water from a pool store!

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    Butterfly's Avatar
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    Re: FC and CYA

    Quote Originally Posted by marjiellen View Post
    I was really freaked out about my high chlorine levels until finding this site! My pool is 18 ft in diameter and 4 ft deep - Vinyl.
    I have a FC of 10 and my CYA is 135.My ph is high ( 8 ) and after reading a bit on this site I am assuming I need to lower the ph, but that FC is fine due to elevated CYA. .... Yes??? The TA is 150.
    Up until about a week ago I was using chlorine tabs in one of those floating chlorine dispensers. I removed them last week due to the FC levels I have.
    Again .. to make sure I am understanding .... with CYA levels high I do not want to continue using the chlorine tabs but instead use bleach. Is this correct?
    How do I know how much bleach to add to maintain chlorine levels for optimum sanitation?
    Welcome to TFP

    With CYA of 135, you really need to do the drain/refill dance and get it down to something reasonable, like 50. CYA may actually be higher because the tests are not very accurate above 90. If you did not do a CYA dilution test, you should.

    If you really want to take control of your pool, you should get one of the recommended test kits. The TF00 is the fav kit around here. Link in my sig.

    And, yes, stop using the tabs. They are what overstabilized the pool and caused the need for drain/refill. Future chlorine should be bleach/liquid chlorine.

    Post any questions you may have and someone will be around to help
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    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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