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Thread: 18 X 36 IG Vinyl Pool Volume

  1. Back To Top    #1

    Join Date
    Jun 2008
    Near Knoxville TN

    18 X 36 IG Vinyl Pool Volume

    The calculations which are provided by most sites is a simplified 1/2 the volume of "box". There are a few that try to include a fudge factor for the hopper designs by multiplying by .85. Anyway back some 15 or so years ago when I had the pool built I had sat down and calculated a volume and somehow concluded 23000 gal. Having come up short on my shocking quantities I was thinking I was off. So this morning I attempted this again. After much thought and trying to visualize the geometric shapes at the intersecting hopper sides I have come up with 22100 gal based on including steps and estimated equipment volume. I saw a similar post under Chemistry 101 which vendor info for a 18X36 was just over 19000 gal. Has anyone ever drawn this out and performed a similar calculation? By the way I found that my deep end was only 7'8" versus 8'. Anybody else's like that?
    18X36 IG vinyl 22100 gal. 1.0 HP Hayward Pump w/300# Hayward sand filter.

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: 18 X 36 IG Vinyl Pool Volume

    Any measurement is going to be an approximation. If nothing else, the water level changes over time to some extent. Beyond that, the depths and slopes involved vary from pool to pool, so it is difficult to generalize any more accurately than the 0.85 fudge factor.

    The approach I normally recommend is to guess at an average depth for the deep end, average that with the depth for the shallow end and then plug your numbers into my Pool Calculator, see the link in my signature, in the Estimating pool volume section near the bottom. Then watch what effects adding chemicals have and adjust your estimate up or down based on chemical additions have too little or too much effect. You only really need to be within +-10% on your size estimate for calculating chemical usage.
    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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