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Thread: When to stop shocking

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    botanica37's Avatar
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    When to stop shocking

    I've been shocking my pool for full 9 days now since I opened it. I raised the FC from 0 to 16 and have kept it there. For the past few mornings, the FC would be 14 and then I would raise it to 16, same in the evening (FC 14). It seems that I lose 2ppm overnight, but my CC is 0. Should I keep the level at 16 until it stays there overnight or since the CC is O, I can assume all is well and let it go down? btw, we had a lot of rain in the past week.

    FC 16
    CC 0
    TA 80
    CH 280
    CYA 50

    Thank you!
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    frustratedpoolmom's Avatar
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    Re: When to stop shocking

    Hi. Okay, so to clarify...

    You test in the evening, and if the FC is below shock level, so you are adding more chlorine to bump it back up to 16. Are you restesting 1 hour after adding the bleach, to make sure you are reaching 16? The final number is what you should compare to the morning test.

    If not, try that. You may not have been reaching 16, and may not actually be seeing an overnight drop.

    In the morning, are you testing before the sun hits the pool?

    The criteria is 1ppm or less FC loss overnight. Anything more than that and you are still supposed to shock.
    Helpful links: Pool School; CYA/Chlorine Chart
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    Butterfly's Avatar
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    Re: When to stop shocking

    I like Chem Geek's (Richard's) criteria of when you are done shocking:

    The process is complete when:
    A. You hold FC loss to 1.0 or less overnite
    B. Your CC's test .5 or less
    C. Your water is sparkling

    According to the CYA/Chlorine chart, shock level for your CYA of 50 is about 20 (Pool Calculator 16). You may want to bump it to 20 and see if that does the trick.

    Don't forget to brush!

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    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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    botanica37's Avatar
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    Re: When to stop shocking

    This morning it was 14 (that was around 8, but it is cloudy, so I am assuming the sun is not to blame for the drop), and I added a 1.82 bottle of bleach, doublechecked the count about 2 hrs later and the FC was 16.5. I never get around to double check at night after adding the bleach, but for the past week it has been fairly consistent drop and add on amount both morning and evening. I've been brushing the pool daily, sometimes twice, because I tried adding cal-hypo to bump the CH up and get the shock level, but it wouldn't disolve, so I brushed and brushed while switching back to bleach. I will try to bump the FC to 20 then and see what happens.
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    rogerbrks's Avatar
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    Re: When to stop shocking

    exit stage right
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    frustratedpoolmom's Avatar
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    Re: When to stop shocking

    Quote Originally Posted by rogerbrks
    I have seen it sparkling clear once but I was using Cal-Hypo to clorinate and of course my CH is high. Since I started using Bleach (6%) it has had a a beautiful blue shade to it. Should I be worried of an algae outbreak? I have white plaster.
    If you are having water clarity/balance issues with your pool you should begin a new thread and post a full sets of results.
    Helpful links: Pool School; CYA/Chlorine Chart
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    Re: When to stop shocking

    NUMBER ONE QUESTION........How does your water look?

    If it looks good, your CC's are obviously .5 or less, and you are only losing 2ppm overnite....I would attribute that slightly excessive loss to the contaminants that have enterd your pool from the rain and let the FC come on down to 3-5ppm.

    For the past few mornings, the FC would be 14 and then I would raise it to 16, same in the evening (FC 14). It seems that I lose 2ppm overnight,
    Just to clarify, the way you confirm overnite loss is by testing in the evening and then testing in the morning with no additions in between. Your statement could indicate you're losing 2ppm daily.....I'm not sure.
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    botanica37's Avatar
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    Re: When to stop shocking

    I still can't get the handle on the shocking part. We had so much rain lately that almost every couple of days I had to drain the pool in the middle of the night to prevent overflowing. Keeping the FC stable overnight is just not happening, there are either too many worms in the pool after the rain or leaves/pollen/flowers. I am vacuuming and brushing daily. So far I had the FC b/n 14-20 for about 3 weeks - is there any potential downsides to keeping chlorine that high for so long?

    Should I let the levels drop to normal and wait for a dry spell to shock the pool? The water looks very nice when I use bleach and kind of murky when I use Cal-hypo, but I am assuming that is from the color of the Cal-hypo itself (nasty grayish). This morning results:

    FC 16
    CC .5
    PH 7.5
    TA 80
    CH 270
    CYA 50
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    JasonLion's Avatar
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    Re: When to stop shocking

    If the water is clear then you can stop shocking, but given the storms and debris you describe it would probably be best to keep the FC level a bit higher than normal until the weather clears up.

    If the water is still murky then I would continue shocking.
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