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Thread: Strange results in alkalinity

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    Strange results in alkalinity

    I just ran a test this morning of my pool water using tf100 kit.

    Results
    Fc - 6.5
    Cc < .5
    Ta - 90
    Ph 7.5
    Cya - 90

    I wanted to lower my ta to about 70. Per the pool calculator I used 48 ounces of muriatic avid to lower my ph. This wasdone around 11:30 this morning.

    I just tested my pool again and now have results below
    Fc 8 (need to adjust SWG %)
    Cc < .5
    Ta - 110
    Ph 7.3 (I've been running waterfall since 11:30 to aerate)
    Cya (didn't retest)

    I tested my ta again thinking I did something wrong, but got same results

    Is there a period that would give me a false ta reading after adding the acid that I should have waited to test?
    22,300 gallon Inground Vinyl Liner pool
    Hayward DE 3620 filter Hayward Ecostar Variable Speed Pump
    1 Skimmer, 2 Main Drains, 2 Returns, 2 step Jets, 8 ft x 3ft waterfall

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    Mod Squad jblizzle's Avatar
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    Re: Strange results in alkalinity

    You should only have to wait about an hour.

    Are you wiping the tip of the bottle between drops? Do they all look the same size and slightly hang on the tip of the bottle?
    extended-test-kit-directions-t25081.html#p206395
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  3. Back To Top    #3

    Re: Strange results in alkalinity

    I did do it for the second test that resulted in the 110 reading. Being that it was higher than originally thought I carefully double checked the test by meticulously following the extended testing steps.
    22,300 gallon Inground Vinyl Liner pool
    Hayward DE 3620 filter Hayward Ecostar Variable Speed Pump
    1 Skimmer, 2 Main Drains, 2 Returns, 2 step Jets, 8 ft x 3ft waterfall

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    Richard320's Avatar
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    Re: Strange results in alkalinity

    Is there any scale in that pool that you might be dissolving back into solution?
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Strange results in alkalinity

    None that I had noticed. Only place I could think of scale would possibly be on rocks from waterfall. I hadn't run it in a week or so, and I hadn't looked at it up close prior to starting it up today. I'll retest in the morning and take it from there.
    22,300 gallon Inground Vinyl Liner pool
    Hayward DE 3620 filter Hayward Ecostar Variable Speed Pump
    1 Skimmer, 2 Main Drains, 2 Returns, 2 step Jets, 8 ft x 3ft waterfall

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    duraleigh's Avatar
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    Re: Strange results in alkalinity

    I wouldn't overthink that TA discrepancy too much. It is quite possible the first test had some testing error. The accuracy of the test is plus or minus 10 ppm. Assuming you get 100 or so again, just ignore the first test.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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