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Thread: Proper FC shock number?

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    Whidster's Avatar
    Join Date
    Mar 2011
    Camas, WA

    Proper FC shock number?

    Our pool suddenly jumped to a FC of 6, CC of 1.5 & TC of 7.5 which means it needs to be shocked. Not sure why, haven't had the CC's jump like that all season. With a CYA of 80, Ph of 7.6 the Chlorine / CYA chart by ChemGeek says shock it to 31. The Pool School chart says the same thing. pool-school/chlorine_cya_chart_shock When I use The Pool Calculator, it says it should be 21 in the "Suggested FC Levels" part toward the bottom. I am wondering why the pool calculator shows a lower number than the other two charts. What do you recommend?

    David Ableidinger
    20,000 Gallon Vinyl Splash AG pool. Goldline SWG. Two sand filters w. 1.5HP Sgl Spd pumps. Lexan Aqua Shield dome. Solar heating, with propane back-up.
    Camas, WA

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    BoDarville's Avatar
    Join Date
    Jun 2012
    DFW, Texas

    Re: Proper FC shock number?

    Both will work. The higher level on the chart works more quickly.
    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
    A good test kit is an investment, not an expense.

  3. Back To Top    #3

    Re: Proper FC shock number?

    If you're using a dome, or cover, then the CCs can build up if there is heavy pool use. The UV in sunlight usually helps break down the CC, but if the UV is blocked, then CCs can take longer to remove.
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