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Thread: Shocking and FC

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    Shocking and FC

    I have been shocking my pool for over a week. I still am having 4-5 ppm chlorine loss overnight. I am getting tired of buying 12 bottles of bleach at a time. Shock level for our pool is 18. By morning I am down to 14 usually. Then I start the process over and add to get my level back up. Help! When is this going to stop?? Pool is crystal clear

    FC 18
    CC 0.5
    Ph 7.5
    CYA 60
    18x36 25,000 gallon, vinyl liner, 1.5HP Super Hayward, Cartridge Filter
    step jets, 2 main drains and skimmer, we have a chlorinator

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    Butterfly's Avatar
    Join Date
    May 2007
    South Carolina

    Re: Shocking and FC

    Try increasing your shock level to 24, based on the Chlorine/CYA Chart in Pool School.

    Also, have you brushed and checked behind light niches, ladders, and any sneaky place algae can hide?
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    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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  3. Back To Top    #3
    benavidescj's Avatar
    Join Date
    Apr 2010
    Fleming Island, FL

    Re: Shocking and FC

    With a CYA of 60 your shock level is actually 24 ppm. But it sounds like you are close. When shocking you need to maintain the shock level consistently or it will take longer. After the FC drops below shock level for your CYA it is not as effective and takes longer. If you need to walk away try and get the FC higher than 24, say 30 so you have some buffer.
    Pool: 28,000 gallons IG; IC 40 SWG; Pentair 120 gpm cartridge filter; Marble finish; Pentair Wisperflow 1.5 hp; Polaris 360
    Spa: 350 gallon; Bromine
    How to shock your pool

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    Join Date
    Apr 2011
    Lynchburg VA

    Re: Shocking and FC

    I agree, bump your FC level a little over the shock level to give yourself some wiggle room. The harder you hit it and stay on top of it maintaining the shock level the faster the process will be. I went through the shock process earlier this year so a similar sized pool and it took over 2 weeks.
    18x36 Vinyl In-ground w/roman ends 27,400G, Hayward 3/4hp with 300# sand filter. Hayward heat pump heater

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  5. Back To Top    #5

    Join Date
    May 2011
    Clearwater, FL.

    Re: Shocking and FC

    Hi brh,
    My pool is way smaller, but was a mess when I started to clean it up the TFP way once I got my TF-100-XL kit.
    Some of my problems were from the stock small filter cartridge not getting clear, but a lot was when the FC was falling below my shock value while at long work days, 9-10 hours.
    One of the mods suggested to go 3 to 4 over my shock level to overcome my falling level when I was away.
    That did the trick in the next 2-3 days, with a filter sock over the bucket skimmer!
    Pool cleared right up and passed all 3 tests!
    Hope this might help you. Oh, I also was reminded to have some POP! (pool owner patience)

    Swim n Play 21' round, expandable 72" liner, 6FT deep center, buried 14", 12,750 Gallons
    Waterway 1HP-2 speed with 22" Sand filter
    TF-100 test kit
    Thanks to TFP my pool is perfect all the time :party:
    I now suffer from Sparklypoolitis! :whoot:
    I am a Platinum contributor because I want everyone who comes here to Trouble Free Pool to have the same success that I enjoy with my pool and family.

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