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Thread: Trying to shock

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    Trying to shock

    So last night I put 11 lbs of DiChlor in my pool. Got a CL reading ot 12 when I went to bed, but this morning it's back to 0! Can that be correct? I'm having a tough time getting this pool back in order!

    FC 0
    TC O
    TA 90
    CYA 45
    PH 7.0

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    SW Indiana

    Re: Trying to shock

    Yes it can. When you have problems, you may need to test and add chlorine every hour at first to get it to hold. The organic load in the pool consumes chlorine quickly.

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    dmanb2b's Avatar
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    Apr 2009

    Re: Trying to shock careful your CYA does not climb above 70 if you want to keep using dichlor. The more CYA you add, the higher your shock level will be. You may want to finish the shocking process with liquid chlorine and then adjust CYA when you're done shocking.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    Re: Trying to shock

    Any ideas on how much chlorine this is going to take? Also, how long do I need to wait after adding CL to test?

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    Mod Squad Bama Rambler's Avatar
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    Jun 2009
    SouthWest Alabama

    Re: Trying to shock

    There's no way to tell how much chlorine or time it will take to get past this. It all depends on how much you have to kill and how serious you are about keeping at it. I'd start by getting 15 large jugs of bleach.

    Test the FC and add enough to get to shock level, wait an hour and test and add again. After several rounds of testing & adding you'll notice that the FC doesn't drop much so you can lengthen the time between testing and adding.
    Dave J. TFP Moderator
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    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Trying to shock

    I know you didn't ask, but don't use any more dichlor. It will likely raise your CYA too high. Use Clorox.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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  7. Back To Top    #7

    Re: Trying to shock

    Well, so far testing on the hour, FC has always only been to about 4-5. Im on 2nd round of adding 8 jugs of clorox! Am I ever going to get close! What do I do overnight!

  8. Back To Top    #8
    Butterfly's Avatar
    Join Date
    May 2007
    South Carolina

    Re: Trying to shock

    Quote Originally Posted by Bobbystone
    Well, so far testing on the hour, FC has always only been to about 4-5. Im on 2nd round of adding 8 jugs of clorox! Am I ever going to get close! What do I do overnight!
    You should be raising the FC to shock level (about 16 to 20) each time you add bleach/liquid chlorine. ETA: If your CYA is 45, your shock level is about 16 to 20. If you added 11 lbs of dichlor after you tested at 45, then your CYA is now close to 70. Shock level with CYA of 70 is about 20 to 28.

    What to do overnight? Raise it to shock level at the end of your day (tonight) and go to bed. But, some folks choose to/have the option to stay with it all night and continue to test and adjust each hour or so. It is entirely up to you.

    I will say that the more you can do during the time when the sun is off your pool, the faster it will go. That way all chlorine goes to fighting the badies and none is lost to sunlight.
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  9. Back To Top    #9

    Re: Trying to shock

    Here's an update on my first shocking. Woke up this morning and found Chlorine still in the pool! Here are the numbers:

    FC 4
    TC 2
    PH 7.0 (Base demand test took 2 drops)
    CYA 40-50

    Three Questions:

    1. So, I guess I just keep on with maintaining shock level?
    B. Should I go head and bump the PH up?
    iii. How do I use the results of the acid demand test or the base demand test? Is there a forumula for using the number of drops to tell me how much chem to add to achieve the desired result?

    Thanks all for your help. How did people get by before forums?

  10. Back To Top    #10

    Re: Trying to shock

    I suggest leaving the pH alone. 7.2 is ideal for shocking, 7.0 is fine. Notice that it is back to where it was to begin with.

    Shock again to FC 20, recheck after one hour of circulating. Boost FC as needed to try to keep it at 20. It will start holding more and more, eventually you will be able to go several hours between checking. Keep a log book of what you test, what you add, what the prediction is for the addition. Like, test 7:30 AM, FC 4.0, added X oz 6% bleach, goal FC 20. 8:30 AM, FC 15, added Y oz 6% bleach, goal FC 20. It will help you predict when you need to check again.

    The formula for how much to add to the pool is via The Pool Calculator First, input your pool volume, then at the bottom, select for Selected Goal Levels; TFP goals, bleach, vinyl if that is what you have.

    Then input your test data in the NOW column. For the things you are not changing, put the NOW values in the TARGET column also (CYA, CH, pH, TA). Use your Shock FC as the goal, 20. Select for 6% bleach or whatever chemical you are using.

    Moving the cursor over a box will convert that volume into jugs or cups or whatever, be sure to select the correct jug size, big is 182 ox, little is 96 oz.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

  11. Back To Top    #11

    Still Shocking..

    Whew! I've been through probably 50-60 large jugs of bleach! I never seem to be able to get the CL to show up more than 6 or 8. I just tested a few minutes after dumping 4 182oz jugs in and got about the same reading. Am I doing something wrong? or do I just need to hang in there an be patient? I do notice that the algae stains on the steps are changing from a green to a brownish gray so I guess that's a good sign. Im wondering if I can have success before I run out of bleach money or winter's here!

    Here are some pics:

    Thanks guys.

  12. Back To Top    #12
    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Trying to shock

    It might be worth it to investigate stronger chlorine. Sometimes it's cheaper by actual chlorine content than bleach. It certainly will mean less lugging. I found a pool store that sells 4 gallons of 12.5% for $14.43. Plus deposit on the bottles and crate. I just set it down and jab my little handtruck under it and roll it back to the pool shed.
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