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Thread: Algae and FC @19 PPM

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    Join Date
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    Algae and FC @19 PPM

    Heres the short of it. Water is clear with visible algae on bottom and sides (when brushed last nite,green cloud appears).
    I had algae a little over a week ago and dumped 4 lbs of 99 proof dichlor (strong stuff) into pool. I went away on vacation
    for the week and wanted this stuff gone. Tested FC in the morning before I left. 30PPM . Came home yesterday early evening
    with these results using TF-100 kit. FC 19PPM CYA about 90PPM. Ph appears to be 7.5 but who knows with FC so high
    TA is unknown. I used the kit as described. Mixed in chemical solution turns green, slowly add other chemical and solution
    turns yellow (high FC). Color is supposed to change to red to determine TA.After about 30 drops,which would have been
    a TA of 300, I gave up as solution was still yellow? Take care of algae first, then attempt PH and TA adjustments? Oh
    and the CC level was 1PPM but does that matter I can see the algae. Thanks
    16x34 kidney shape 19,000 gal vinyl IG
    Pentair IC-20 SWG
    Pentair sand filter
    Pentair 1HP pump

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    Mod Squad Bama Rambler's Avatar
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    Re: Algae and FC @19 PPM

    First and foremost, you have not shocked the pool. With a CYA of 90 your shock level is 35ppm. You will have to reach, and maintain that level as often as hourly until you pass the OCLT (overnight chlorine loss test). Don't worry about your other levels until you're done shocking.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Algae and FC @19 PPM

    I understand dichlor raises my CYA which I dont want. Im off to get some bleach. The pool calculator is a little
    confusing. If someone could confirm the amount of bleach I need to get my FC up to a shock level of 35 PPM,
    I would appreciate it. Thanks
    16x34 kidney shape 19,000 gal vinyl IG
    Pentair IC-20 SWG
    Pentair sand filter
    Pentair 1HP pump

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    Re: Algae and FC @19 PPM

    It takes 11 gallons (not jugs) of 6% bleach to raise the FC to 35ppm in a 19k pool. Be sure to subtract your existing FC at the time you put the Clorox in the pool so your dosage will be less.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Richard320's Avatar
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    Re: Algae and FC @19 PPM

    Quote Originally Posted by bluskyguy
    I understand dichlor raises my CYA which I dont want. Im off to get some bleach. The pool calculator is a little
    confusing. If someone could confirm the amount of bleach I need to get my FC up to a shock level of 35 PPM,
    I would appreciate it. Thanks
    5 gallons of 6% will bring it up to 35 ppm, at the time you tested FC. Probably more, now.

    What's your Calcium level? You may have "room" to use Calcium Hypochlorite, which is a powder, and therefore easier to carry.
    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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