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Thread: Getting conflicting Ph results from Pool Calculator

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    Getting conflicting Ph results from Pool Calculator

    Hey folks,

    I've got an 24,000 gal vinyl pool.

    My Ph is currently at 6.8. So I went to the pool calculator at: http://www.poolcalculator.com/

    The grid up top tells me that with a 24,000 gallon pool, to go from 6.8 to 7.5, I need to add 280 oz (by weight, 269 oz by volume) of borax.

    But then under the grid it tells me that if I add 220 oz of borax it will raise Ph by 1. According to the above though, nearly 1.5 times that will only raise it by 0.7.

    Am I using the pool calc wrong or am I misinterpreting it or is there a bug?

    What is correct though? How many oz (by weight) of 20 mule team borax would I add to a 24,000 gallon pool to raise the Ph from 6.8 to 7.5? (assuming other levels are good)

    Thanks!
    18 X 36 In-Ground Vinyl Pool, Hayward 1 HP SuperPump, Hayward SP270T 350lb Sand Filter, CompuPool CPSC48 Salt Chlorine Generator, Hayward H400FDN 400 BTU Natural Gas Heater, 2 returns, 1 skimmer, No Main Drain

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    Join Date
    Jan 2009
    Location
    Cupertino, CA
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    1,966

    Re: Getting conflicting Ph results from Pool Calculator

    The answers from the upper section will take your other levels (e.g. TA) into consideration. The answers from the "effects of adding chemicals" section assume nominal values for the other levels. If your actual levels are much different from the assumptions, then the "effects of adding chemicals" section will be off. I would enter all your numbers in the "now" column and trust the results from the upper section.

    But, as with any time you're adding a lot of something, don't do it all at once... do it in a couple stages. Like, shoot for 7.2 first, and see where you end up.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    Re: Getting conflicting Ph results from Pool Calculator

    Thanks! I think too that the bottom results are for a 10,000 gallon pool but it didn't mention it.
    18 X 36 In-Ground Vinyl Pool, Hayward 1 HP SuperPump, Hayward SP270T 350lb Sand Filter, CompuPool CPSC48 Salt Chlorine Generator, Hayward H400FDN 400 BTU Natural Gas Heater, 2 returns, 1 skimmer, No Main Drain

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: Getting conflicting Ph results from Pool Calculator

    Both sections take the pool size into account. The upper section adjusts based on you current TA and Borate levels. The lower section assumes that TA is 100 and Borate is 0.
    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

  5. Back To Top    #5

    Re: Getting conflicting Ph results from Pool Calculator

    Except TA of 100 of Borate of 0 is what I have the top set to as well.
    18 X 36 In-Ground Vinyl Pool, Hayward 1 HP SuperPump, Hayward SP270T 350lb Sand Filter, CompuPool CPSC48 Salt Chlorine Generator, Hayward H400FDN 400 BTU Natural Gas Heater, 2 returns, 1 skimmer, No Main Drain

  6. Back To Top    #6
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887

    Re: Getting conflicting Ph results from Pool Calculator

    There is another effect that the upper section takes into account as well. The amount of acid required to lower the PH by 0.2 varies depending on the starting PH. The lower section doesn't know the starting PH, so it assumes the PH change is symmetric around 7.5.
    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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