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Thread: Alkalinity Question

  1. Back To Top    #1

    Join Date
    Jun 2014
    Location
    Mebane, NC
    Posts
    27

    Alkalinity Question

    Hello All!

    I have had a pool for 15 years but just a few weeks ago gave my pool store the heave hoe and switched from trichlor tabs to bleach.

    I see in the Pool School that the recommended level of TA for a vinyl pool is 70-90+ but to ask the forum for advice on what would be ideal for my pool. It runs east to west on the southern facing side of my house so it gets lots of direct sun. My water test results from this morning are below.

    In all the years of the pool store water testing they always had two alkalinity results, a Total Alkalinity result an an adjusted alkalinity result. They always used the adjusted result for making any recommendations. I now have a Taylor K-2006 test kit and it came with a book "Pool & Spa Water Chemistry" that gives a formula and chart to use to get an an adjusted alkalinity result.

    When posting TA should I use the results I get from the test or should I use the formula and use the adjusted result?

    My pool is crystal clear.

    Water Temp - 86f
    FC - 4.5ppm
    CC - 0ppm
    PH - 7.7
    TA - 120ppm (109.8ppm is adjusted result using the formula from Taylor)
    CH - 80ppm
    CYA - 35ppm

    Do I need to do anything?

    Note: I have not put any Borax in my pool as I have not had to increase PH ( I have some on hand though as well as baking soda)


    Thanks in advance!
    18360 gallon; Vinyl IG; Pentair SuperFlo High Performance Pump w/3HP ecotech EZ variable speed motor; Hayward S-200 sand filter; Dolphin Supreme M4 cleaning robot; Taylor K-2006 test kit

  2. Back To Top    #2

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082

    Re: Alkalinity Question

    The Total Alkalinity only needs to be adjusted when calculating a saturation index for calcium carbonate. Our TA recommendations and the calculations in PoolMath automatically account for the recommended or entered CYA and Borates levels that adjust the TA for the Calcite Saturation Index (CSI) calculation. In other words, don't worry about adjusting the TA for calculations.

    As for the actual TA level in your pool, the only reason to lower it (since your CH is low since you have a vinyl pool) would be if you find the pH is rising over time too much to your liking. A lower TA will have less carbon dioxide outgassing that causes the pH to rise. Whereas your Trichlor tabs were acidic, the use of bleach is roughly pH neutral but carbon dioxide outgassing from the pool causes the pH to rise. So it's up to you as to whether you want to use the procedure to Lower Total Alkalinity or just want to see how things go. If you add acid over time to maintain the pH, your TA may drop anyway unless you have evaporation and refill with water high enough in TA.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  3. Back To Top    #3

    Join Date
    Jun 2014
    Location
    Mebane, NC
    Posts
    27

    Re: Alkalinity Question

    Thanks Chem Geek! I'll just stay where I am at and see how things stay.
    18360 gallon; Vinyl IG; Pentair SuperFlo High Performance Pump w/3HP ecotech EZ variable speed motor; Hayward S-200 sand filter; Dolphin Supreme M4 cleaning robot; Taylor K-2006 test kit

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