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Thread: Calculate Pool Volume from FC

  1. Back To Top    #1

    Join Date
    Jun 2011
    San Diego California

    Calculate Pool Volume from FC

    I'm new, so if this makes no sense, that's why.

    I've used the online pool volume estimators to get an appoximation of my pool volume. Its an irregular shape, so short of doing the Integral Calculus to determine the volume, I've been roughing it.

    Yesterday I measured FC after the sun was down and it was 6ppm. I wanted to target around 12 or there about. I added enough bleach to do so (6% of clorox volume) by assuming the pool volume was close. After adding the bleach, and letting the pump run 2 hours, I measured the FC again before heading to bed. It was 20ppm with 0 CC. I checked thismorning, and it was still 20ppm with 0CC.

    Therefore, I assume I can get a more realistic total pool water volume by the following;

    (2.84gal bleach X 6%) = 0.1704 gal of Chlorine
    20FC - 6FC = 14 ppm increase in Chlorine when adding 0.17gal of Chlorine

    This would imply the total volume is;

    Total Volume = 0.17gal X 1,000,000/14ppm

    Total Volume = 12,142 gallons.

    Up until now, using online calculators, I had assumed my pool was 22,000-25,000. If my PPM approach is correct, its only half that. Given I was expecting an increase of 7ppm, and received instead 14ppm, this would make sense.

    My pool is as follows;

    length - 38'
    max width - 19'
    min width - 15'
    Max depth - 8.5'
    Min depth - 3'

    The 3' depth carries to 4' deep across half the pool, and then sinks quick to 8.5'.

    I think given my ppm experience, I should be assuming a pool volume of 12,000 gallons, unless there are other factors influencing this?

    Another item that comes to mind is when I drained and re-filled the pool, I measured the flow from one hose to be 10 gal/min (2 X 5gal buckets I measured). I had multiple hoses and when I did the math, I assumed it would take 8.5 hours. I went to bed and set the alarm for 4 hours later to check on it. When I checked, it was about 30 min from being completely full. Hence, about half what the online calculator was suggesting.
    IG, 13,000 gal, concrete, DE, VS Intelliflo Pump, Intellichlor SWG

    San Diego, Ca.

  2. Back To Top    #2

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Calculate Pool Volume from FC

    I haven't looked carefully at the math but that pool is w-a-a-a-ay bigger than least 20k plus.

    Using FC to calculate volume has way too many variable to be at all dependable. If you can post a drawing of your pool, we can help figure the rough gallons, but 12k won't work.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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