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Thread: Hello.. confused over how to read the chlorine/CYA chart..

  1. Back To Top    #1

    Join Date
    May 2015
    Wallingford, CT

    Hello.. confused over how to read the chlorine/CYA chart..

    Hello there! I'm very new at this, and have a kind of a 'stupid' question.
    On this chlorine/CYA chart I see ...
    DO I read it like this -
    If I can get my CYA to the target of 30, therefore my target FC will be 4. and to get to the target FC of 4 I need to add enough shock to get the FC level to 12 for a while?

    This doesn't exactly made any sense to me.
    Can anyone tell me how to read this thing, I'm feeling dumber by the moment.
    I actually used to like math.

    two days ago my CYA was at 0
    and my chlorine level was at 0
    we added 'stabilized chlorine' that we had, until I could get a handle on how to read and understand this stuff.
    Boyfriend says the chlorine was at 4 yesterday when he tested.
    Thank you very much
    I believe 18,500g, AG
    round :)

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Hello.. confused over how to read the chlorine/CYA chart..

    With CYA at 30, normal minimum FC is 4. You should try to never let it drop below that. But you will lose some chlorine to sunlight every day, so you target 6 so that it doesn't drop below 4 before you test and add again. If you get careless and do develop algae, you will need to raise the FC level to shock level to kill it off faster than it can reproduce. Shock level for 30 CYA is 12 FC. Unless you get algae, you may never ever need to go that high.

    Whatever your CYA level is as it's rising, when you add more chlorine, aim for the target
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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  3. Back To Top    #3
    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    DFW, TX

    Re: Hello.. confused over how to read the chlorine/CYA chart..

    Welcome to TFP!

    Just to make it official, 0 FC is not enough! If your FC is at 0 run for the bleach bottle, stop by Poolmath and add some pronto.

    Richard is looking at the wrong line on the CYA chart.

    CYA of 30 has a minimum of 2, a target of 4 and shock of 12. So, never ever let it drop below 2. Target keeping it at 4, I would go 5 because I hate algae. And if you need to SLAM your pool the shock level will be 12. Clear? Like a pool?

    It is safe to swim in your pool when:
    Chlorine level is above the minimum and below shock level for your CYA
    PH is between 7.2 and 7.8
    Water is clear

    Here is some Pool School for you to read.
    Pool School - ABCs of Pool Water Chemistry
    Pool School - Recommended Levels
    Pool School - Recommended Pool Chemicals
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