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Thread: Shocking and some questions

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    Join Date
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    Shocking and some questions

    So over the course of the weekend the pool became somewhat cloudy. Could still see the bottom but I had the feeling I was looking through glass that was not clear.


    So I did the OCLT:

    Sunday 9PM:
    FC 9.5
    CC 0.5

    Monday 6AM
    FC 8.0
    CC 0.5

    So since my CYA level is between 60-70, I brought my FC levels up to 28 on Monday morning. Testing through out the day found me adding about 2 cups 6% bleach every 2-3 hours. Brushed the pool twice and vacuumed in the evening. The water cleared up significantly in the first 4 hours of shocking.
    Now on to last night's test and my question:
    Monday 9PM
    FC 28.5
    CC 0.5

    Tuesday (today) 6AM
    FC 26
    CC 0.5

    We had a little shower last night. Would that rain affect my FC values? I seriously doubt it was more than 0.5 inch, but just wondering. We don't get much rain here, except this time of year the monsoon, so I haven't had the chance to observe how the rain would affect FC.

    Second question:
    Why in the world did my chlorine loss go UP the second night. I'm not seeing any algae per se. Just had that cloudy appearance to the water. I assumed my chlorine loss would go down the second night, unless it has something to do with being at shock value the second night? So there was more free chlorine available to fight whatever it is?
    Cindy

    4.8 K gallon AGP: sharkline opera 12'x17'x52"
    Sandpro 4511 sand filter and pump

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    Mod Squad JohnT's Avatar
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    Re: Shocking and some questions

    Within the 0.5ppm resolution of the test, your overnight drops are pretty much the same. Rain tends to wash dirt and debris into my pool, which is going to consume some chlorine too.
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    Re: Shocking and some questions

    So you're saying that the 1.5 ppm loss the first night and the 2.5 ppm loss the second night are basically equivalent because of +- of 0.5 ppm?
    Cindy

    4.8 K gallon AGP: sharkline opera 12'x17'x52"
    Sandpro 4511 sand filter and pump

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    Mod Squad JohnT's Avatar
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    Re: Shocking and some questions

    Quote Originally Posted by crs16
    So you're saying that the 1.5 ppm loss the first night and the 2.5 ppm loss the second night are basically equivalent because of +- of 0.5 ppm?
    Pretty close to it. I wouldn't be concerned, especially if the pool is looking better.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Shocking and some questions

    Thanks John. The pool is looking much better.

    One further question, my cya is between 60 and 70. (I have a hard time doing that test, but consistently between 60 and 70.)

    Twice last week the FC had dropped to 4.5 in the evening before I added more chlorine. I'm trying to figure out why it got cloudy again. I add enough chlorine in the evening to hit a target of 9, well maybe between 8 and 9 and by sundown the following day it drops to 5 and sometimes to 4.5. Should I try to keep it a bit higher by adding some chlorine in the middle of the day? And make sure it doesn't drop down to 5? I'm a stay at home mom who homeschools, so it wouldn't be a problem to pop out there in the middle of the day to do it.

    This is the second time we've had the cloudy water issue (since we set up the pool at the beginning of the month), and I'm wondering if dropping to 5 is too low.

    Thanks a lot John!
    Cindy

    4.8 K gallon AGP: sharkline opera 12'x17'x52"
    Sandpro 4511 sand filter and pump

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    Re: Shocking and some questions

    If you lose 1 ppm or more of your FC overnight, you need to shock your pool. Being at 8 or 9 ppm of FC in the evening and being at 5 ppm in the morning means that your water is dirty and the pool needs to be shocked. Shock until your FC holds to 1 ppm of FC loss or less overnight, a CCof 0.5 or less, and your water gets clear. If your water doesn't meet all three of these criteria, then you need to continue shocking until they are met.

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    Re: Shocking and some questions

    Quote Originally Posted by 257WbyMag
    If you lose 1 ppm or more of your FC overnight, you need to shock your pool. Being at 8 or 9 ppm of FC in the evening and being at 5 ppm in the morning means that your water is dirty and the pool needs to be shocked. Shock until your FC holds to 1 ppm of FC loss or less overnight, a CCof 0.5 or less, and your water gets clear. If your water doesn't meet all three of these criteria, then you need to continue shocking until they are met.

    Oh yes. I think you misunderstood, I am still shocking. I have my FC at 28 and check it every couple of hours during the day. Bring it back up to 28 after sundown and do an OCLT in the morning. I understand that.

    I'm trying to figure out what my ideal conditions should be to prevent this annoying cloudiness in the future. Twice in one month is bugging me. My CYA is between 60 and 70. As a normal operating procedure I had been adding enough chlorine in the evening to bring my FC up to 8 or 9 ppm. The next evening when I check I'm typically around 5 ppm. Although 2x this past week my FC level dropped to 4.5 in the evening when I checked it. I'm asking if I should try boosting the chlorine around midday so it doesn't get as low as 5 in the evening. Would that help prevent the clouding problem we've been having?
    Cindy

    4.8 K gallon AGP: sharkline opera 12'x17'x52"
    Sandpro 4511 sand filter and pump

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    Mod Squad zea3's Avatar
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    Re: Shocking and some questions

    For a CYA of 60-70 your shock level is 20 and your normal range is 5-10. After you complete the shock process try to keep the FC at 10. Once you pass the the overnight test you should notice your chlorine lasting longer. When you are on the verge of a full fledged algae bloom the water will be slightly cloudy and you will consume more chlorine than normal. You will see a difference in how the pool performs after all the algae is gone. Be sure to brush the pool and look for areas where algae can hide (like behind pool ladders/steps) and scrub them well to get rid of algae.
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