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Thread: High CYA low Fc

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    High CYA low Fc

    I am having an issure with keeping a FC level in my pool. I have been shocking with Dichorl and using trichlor tabs. My CYA is now at 150. We have pumped off several gallons of water and refilled, but it didn't help with the cya. Is there anything, besides draining the pool, to do.

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    Join Date
    Feb 2008
    Denton, TX

    Re: High CYA low Fc

    Welcome to TFP!

    The only way to remove CYA is to drain water and replace it. Not sure what kind of pool you have but if it is above ground, I would only do about a third at a time to keep from messing the liner up. If your pool is inground, then use care as well if your water table is high in your area. For a non saltwater pool, you want your CYA down to between 30 and 50. Stop using stabilized chlorine sources like dichlor or trichlor and use bleach instead.

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    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: High CYA low Fc

    What he said.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: High CYA low Fc


    Yeah, they covered it. You'll need to replace a whole bunch of water. Have you studied ?
    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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    Join Date
    Jun 2012
    Howell, NJ

    Re: High CYA low Fc

    Also, do you have your own test kit? That will be needed to follow the shock process, which you will have to go through (after draining a lot of water).
    7 year old ~13,500 gal 24' AGP with 1.5 hp Proline pump, 150 sqft Pleatco cartridge, filled with well water with pH of about 4.5.
    Wanda the Whale pool vacuum, home made heater, Taylor K-2006
    Cloudy Pool? 1) Order test kit. 2) Follow SLAM
    New to TFPC? Read Pool School a few times, then post questions. PoolMath will help with chemical additions.

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    Re: High CYA low Fc

    Ok, I have taken all the trichlor tabs out of the skimmer and started shocking with bleach. I am able to hold a high chlorine level overnight now. I have been reading all the info in Pool School. My CYA is still around 150. My Pool is crystal clear. I have in inground 20x40 vinyl liner and sand filter pool.
    I do not want to drain the water down in my pool and refill as that will cost a lot of money. My question, Do I need to maintain a fc level of at least 7 even though my pool is crystal clear? I live in Middle Tennessee and the temp of the pool is around 75 now.

  7. Back To Top    #7
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: High CYA low Fc

    Water is not nearly expensive as most people think ... averages around $5/1000 gallons.

    At 150ppm CYA, you need to maintain at least a FC of 11ppm according to the poolcalculator to prevent algae from starting.

    Best to replace water.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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