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Thread: FC Question

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    FC Question

    I ordered the test kit here a few weeks back.
    FC is 1.5
    TC 2 or less
    TA 90
    PH 7.4 or so
    cya 50

    looking at the Non swg pool cya/ch chart it has FC6 as the target...is this correct? I've been maintaining FC 1.5

    I use 1/2 cup liquid shock nightly to maintain 1.5 for 10500 gal above ground pool. Water has been crystal clear.

    Please comment, thanks.
    15000gal IG plaster pool, cartridge filter

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    reebok's Avatar
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    Re: FC Question

    what is liquid shock? anything with shock in the name is really a misnomer. I assume it's liquid chlorine?
    are you using any other products? algaecides, phosphate removers, clarifiers, etc?
    if you want to maintain your pool with chlorine, acid and probably not much else, and be guaranteed to not have algae (assuming good filtration, circulation and brushing) then you need to maintain your fc level according to the chart you referenced.
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    Re: FC Question

    Quote Originally Posted by reebok
    what is liquid shock? anything with shock in the name is really a misnomer. I assume it's liquid chlorine?
    are you using any other products? algaecides, phosphate removers, clarifiers, etc?
    if you want to maintain your pool with chlorine, acid and probably not much else, and be guaranteed to not have algae (assuming good filtration, circulation and brushing) then you need to maintain your fc level according to the chart you referenced.
    I'm only using BBB and acid...the liquid shock I mentioned is 12.5 percent sodium hypochlorite.
    15000gal IG plaster pool, cartridge filter

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    JasonLion's Avatar
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    Re: FC Question

    With CYA at 50, you want to keep the FC level at 4 or higher at all times. Depending on your pool, you will need to raise FC up to somewhere between 6 and 10 daily in order to keep FC at 4 or higher at all times.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: FC Question

    Quote Originally Posted by JasonLion
    With CYA at 50, you want to keep the FC level at 4 or higher at all times. Depending on your pool, you will need to raise FC up to somewhere between 6 and 10 daily in order to keep FC at 4 or higher at all times.
    Just so I'm clear the results in the blue taylor test kit from the larger test kit should read 4 or higher daily?

    Many thanks
    15000gal IG plaster pool, cartridge filter

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    JasonLion's Avatar
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    Re: FC Question

    The chlorine test in the Taylor K-1000 (drops turn the sample various shades of yellow) is an OTO test. Most people can not reliably distinguish chlorine levels above 2 from each other using that test.

    What is normally done in this situation is to use the full FAS-DPD chlorine test (powder turns the sample pink and drops eventually turn it clear again) for several days, while working out what amount of chlorine you need to add so that the FC level is 4 or higher the next evening. Once you have that worked out, you can use the simpler OTO test to just make sure that FC is above 2 most days and simply add the "usual" amount of chlorine, and then about once a week use the FAS-DPD test again to verify that you are still at 4 or above (adjusting the amount of chlorine you add daily if you are out of range in either direction).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: FC Question

    Quote Originally Posted by JasonLion
    What is normally done in this situation is to use the full FAS-DPD chlorine test (powder turns the sample pink and drops eventually turn it clear again) for several days, while working out what amount of chlorine you need to add so that the FC level is 4 or higher the next evening. Once you have that worked out, you can use the simpler OTO test to just make sure that FC is above 2 most days and).
    That is the test I do weekly and I did it today with a 1.5 FC. For some reason I thought 1.5 was the level I needed to maintain. At what level is there too much chorine? Thanks again for your help.
    15000gal IG plaster pool, cartridge filter

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    reebok's Avatar
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    Re: FC Question

    in your situation, anything above 20ppm. so yes, there's a lot of room.
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    Re: FC Question

    Quote Originally Posted by jjpaul
    I ordered the test kit here a few weeks back.

    looking at the Non swg pool cya/ch chart it has FC6 as the target...is this correct? I've been maintaining FC 1.5
    jjpaul, as you have already said in your first post the chart says FC6 so that is your answer. The chart was written by very knowledgable people.

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    JasonLion's Avatar
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    Re: FC Question

    There is a lot of bad advice in the pool industry. FC at 1.5 is a great recommendation when CYA is zero in an indoor pool, but it is completely inappropriate for an outdoor pool with CYA around 50.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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