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Thread: FC after shock

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    FC after shock

    Trying to see how many gallons of liquid bleach to add with the calculator. What is the normal target level for FC when you shock. I have lost of algae.

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    Richard320's Avatar
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    Re: FC after shock

    Target level depends on CYA level.

    Can you post test results?
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: FC after shock

    Quote Originally Posted by Richard320
    Target level depends on CYA level.

    Can you post test results?

    Added 8 lbs. to raise the cya levels Saturday night. Still reads 0. pool is 23,000 gallons. FC is 0 and the algae are loving it.

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    Richard320's Avatar
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    Re: FC after shock

    Quote Originally Posted by chrisgjim
    Quote Originally Posted by Richard320
    Target level depends on CYA level.

    Can you post test results?

    Added 8 lbs. to raise the cya levels Saturday night. Still reads 0. pool is 23,000 gallons. FC is 0 and the algae are loving it.
    4 lbs only brings CYA to 21, which is below the tester's ability to measure. Shock level is 12 for that CYA.

    I'd suggest adding another two pounds of stabilizer to get CYA up to 30ish, which will raise shock FC to 14. The higher FC level is offset some by the better UV protection.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: FC after shock

    Quote Originally Posted by Richard320
    Quote Originally Posted by chrisgjim
    Quote Originally Posted by Richard320
    Target level depends on CYA level.

    Can you post test results?

    Added 8 lbs. to raise the cya levels Saturday night. Still reads 0. pool is 23,000 gallons. FC is 0 and the algae are loving it.
    4 lbs only brings CYA to 21, which is below the tester's ability to measure. Shock level is 12 for that CYA.

    I'd suggest adding another two pounds of stabilizer to get CYA up to 30ish, which will raise shock FC to 14. The higher FC level is offset some by the better UV protection.


    The calculator says that I need almost 6 lbs to get the CYA to 30. I already added 8 lbs. and what I understand it may take a week for it to dissolve. You think I should add another 2 lbs of stabilizer?

    Last night I added 2 lbs of 72% powder shock and that did nothing. I was going to get liquid shock today, because in the past that always worked to the best. In the past out pool store told us to add 8-12 gallons of shock, the calculator is saying just under 3 gallons.

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    Richard320's Avatar
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    Re: FC after shock

    Quote Originally Posted by chrisgjim
    Quote Originally Posted by Richard320
    Quote Originally Posted by chrisgjim
    Added 8 lbs. to raise the cya levels Saturday night. Still reads 0. pool is 23,000 gallons. FC is 0 and the algae are loving it.
    4 lbs only brings CYA to 21, which is below the tester's ability to measure. Shock level is 12 for that CYA.

    I'd suggest adding another two pounds of stabilizer to get CYA up to 30ish, which will raise shock FC to 14. The higher FC level is offset some by the better UV protection.


    The calculator says that I need almost 6 lbs to get the CYA to 30. I already added 8 lbs. and what I understand it may take a week for it to dissolve. You think I should add another 2 lbs of stabilizer?

    Last night I added 2 lbs of 72% powder shock and that did nothing. I was going to get liquid shock today, because in the past that always worked to the best. In the past out pool store told us to add 8-12 gallons of shock, the calculator is saying just under 3 gallons.
    Ooops. No, I misread that or something. Somehow I thought you added 4 lbs. My mistake. Leave CYA alone.

    With 8 lbs, CYA should be 42, so shock level is 15. Follow the Pool Calculator dosage. In about two hours, your FC will be lower, let the pool calculator tell you how much to add to bring it back up to 15. Overall, I suspect you'll be using more than 12 gallons of liquid, but in doses, not as a blast. Sort of like taking antibiotics. You take them for several days, not all at once.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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