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Thread: How many Gallons of Water?

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    How many Gallons of Water?

    I'm attempting to calculate how many gallons of water are in my pool. I understand the basic formula, but my pool is a bit different (enlarged diving area). I have calculated the number of gallons, but my number does not agree with the pool calculator when adding CYA. I hope the following makes sense...

    Here are the specifics:

    20 feet wide
    40 feet long (plus 4.5 feet single roman end that contains liner covered steel steps (three 10" steps)
    Shallow end is 3.5 feet deep
    Deep end is 10 feet deep

    Going from the diving board to the shallow end:
    -drops from 3.5 feet to 10 feet in a distance of 5 feet
    -10 feet deep for a distance of 10 feet
    -raises up the slope from 10 feet to 3.5 in a distance of 9 feet
    -then goes a distance of 16 feet in the shallow end (plus the 4.5 foot single roman end)

    From side to side in the deep end:
    -drops from 3.5 feet to 10 feet in a distance of 5 feet
    -10 feet deep for a distance of 10 feet
    raises from 10 feet to 3.5 feet in a distance of 5 feet

    Thanks!
    20x44.5 (3.5 feet SE, 10 feet DE), IG, Vinyl, Hayward Cartridge (C4030), 2HP Hayward Super Pump (SP2615X20), 2 main drains, 5 returns, Hayward ColorLogic 4.0, Circu Pool RJ60 SWG, Hayward Heat Pro 140K BTU, Polaris 380, Polaris Booster Pump (PB4-60),

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    snooptodd's Avatar
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    Re: How many Gallons of Water?

    10*18*14+3.5*18*20=3780
    Am I close? I would probably go with 4000 and adjust later if necessary

    27' AG, sand filter, Pentair 340203 Two-Speed 3/4-Horsepower, hard plumbed

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    Re: How many Gallons of Water?

    snooptodd, I have calculated 33,000 to 40K plus. Anyone else?
    20x44.5 (3.5 feet SE, 10 feet DE), IG, Vinyl, Hayward Cartridge (C4030), 2HP Hayward Super Pump (SP2615X20), 2 main drains, 5 returns, Hayward ColorLogic 4.0, Circu Pool RJ60 SWG, Hayward Heat Pro 140K BTU, Polaris 380, Polaris Booster Pump (PB4-60),

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    freqz's Avatar
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    Re: How many Gallons of Water?

    So... 3.5'x20'x40' = 2800 ft^3 is the "top portion" of the pool

    Then you have the "bottom portion" (deep end) underneath that which has an average width and length of 15' and an average depth of 3.25' (because we took the top portion off, see?) or 731.25 ft^3

    Or about 3500 ft^3 total.

    So between 26,000 and 27,000 gallons.
    25000 gal in ground plaster. '79 vintage. Cartridge filter.

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    snooptodd's Avatar
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    Re: How many Gallons of Water?

    Hehe yea I thought 4k was small. I forgot to convert ft^3 to gal. So 3780*7.48=28274

    27' AG, sand filter, Pentair 340203 Two-Speed 3/4-Horsepower, hard plumbed

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    Re: How many Gallons of Water?

    Freqz, how did you get the average depth of 3.25'? I have a 10 foot deep pool (it has a 10x10x10 feet diving well).


    20 x 44.5 single roman end, ~33,000 gallons, 10 feet deep, garrett vinyl liner, Hayward SwimClear Cartridge Filter, Hayward 2 HP Pump, Cirrcupool RJ60 SWG, Hayward 140k BTU Heater, Polaris 380 with Booster Pump
    20x44.5 (3.5 feet SE, 10 feet DE), IG, Vinyl, Hayward Cartridge (C4030), 2HP Hayward Super Pump (SP2615X20), 2 main drains, 5 returns, Hayward ColorLogic 4.0, Circu Pool RJ60 SWG, Hayward Heat Pro 140K BTU, Polaris 380, Polaris Booster Pump (PB4-60),

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    freqz's Avatar
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    Re: How many Gallons of Water?

    Quote Originally Posted by Drsafety View Post
    Freqz, how did you get the average depth of 3.25'? I have a 10 foot deep pool (it has a 10x10x10 feet diving well).
    I was still drinking my coffee. The first pass through that I was assuming flat side when I calculated it and then noticed my error.

    The volume of the diving well would be the volume of a pyramid 20x20 on top and 10x10 on bottom with a depth of 6.5'...or about 1500 ft^3.

    Closer to 33k gallons.
    25000 gal in ground plaster. '79 vintage. Cartridge filter.

  8. Back To Top    #8

    Re: How many Gallons of Water?

    That is what I have been calculating...33,000 gallons. However, when I added 8 pounds of CYA it registered less than 20.


    20 x 44.5 single roman end, ~33,000 gallons, 10 feet deep, garrett vinyl liner, Hayward SwimClear Cartridge Filter, Hayward 2 HP Pump, Cirrcupool RJ60 SWG, Hayward 140k BTU Heater, Polaris 380 with Booster Pump
    20x44.5 (3.5 feet SE, 10 feet DE), IG, Vinyl, Hayward Cartridge (C4030), 2HP Hayward Super Pump (SP2615X20), 2 main drains, 5 returns, Hayward ColorLogic 4.0, Circu Pool RJ60 SWG, Hayward Heat Pro 140K BTU, Polaris 380, Polaris Booster Pump (PB4-60),

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    freqz's Avatar
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    Re: How many Gallons of Water?

    How long did you wait to test the CYA?

    It can take up to a week to register on the test...
    25000 gal in ground plaster. '79 vintage. Cartridge filter.

  10. Back To Top    #10

    Re: How many Gallons of Water?

    10 days


    20 x 44.5 single roman end, ~33,000 gallons, 10 feet deep, garrett vinyl liner, Hayward SwimClear Cartridge Filter, Hayward 2 HP Pump, Cirrcupool RJ60 SWG, Hayward 140k BTU Heater, Polaris 380 with Booster Pump
    20x44.5 (3.5 feet SE, 10 feet DE), IG, Vinyl, Hayward Cartridge (C4030), 2HP Hayward Super Pump (SP2615X20), 2 main drains, 5 returns, Hayward ColorLogic 4.0, Circu Pool RJ60 SWG, Hayward Heat Pro 140K BTU, Polaris 380, Polaris Booster Pump (PB4-60),

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