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Thread: Re: table of FC loss percentages

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    Re: table of FC loss percentages

    Re: chem geek's table of FC loss percentages, posted 07/14/2012

    My recently purchased house came with an 18,000 gal. pool and a CYA level off the chart. I drained 7,000 gal. and refilled, but CYA is still about 150, according to Leslie's. (Leslie's tells me that all other water chemistry #'s are OK.)

    At 150 CYA, the Pool Calculator gives me a FC goal of 11-18.

    Applying chem geek's 7.7% FC loss per day, I calculate that, if I start at FC 18, six days later my FC level will still be slightly above 11. Is this correct?

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Re: table of FC loss percentages

    Yes, and no. Your calculation is correct. However you need to understand that the info in the table is just an average value across many pools. Every pool is going to be different and actual chlorine loss can be much higher or much lower than the nominal level. Chlorine loss varies with many factors, including water temperature, amount of sunlight, clouds/haze, time of year, shading by trees, number of people swimming, amount of wind borne debris entering the pool, and so on.
    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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    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: table of FC loss percentages

    As you read further in the forum, you will find pool store testing is simply not to be trusted. I would never dose my pool based on a pool store test result.....CYA especially.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Re: table of FC loss percentages

    Thanks for confirming the numbers. Now I need to test the water frequently and get a feel for how my other factors impact the FC loss.

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