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Thread: Conflicting pH/Alkalinity tests

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    Conflicting pH/Alkalinity tests

    I have had a trouble free pool for 10+ years, yay. Now we've moved to a new house with a "soon to be" trouble free pool. I've just opened the pool, filled it with well water ( very soft ), shocked it with stabilized Chlorine shock, and I'm running the filter 24/7. It was very green, and now blue and cloudy, so I'm assuming that more filtering will take care of that. I've also got an aquabot running, which gets clogged every few hours, but I can now see the bottom of the pool.
    I've got stablized pucks in the skimmer and floater. I've tested the FC and Combined Chlorine every day. The FC is always very low, but the CC, which shows up after a few minutes as a medium yellow on my test kit seems to be the 2-3ppm range. The pH is very low 6.8 ish, but the alkalinity tests at 130-140??? Not sure how to interpret these results. The CYA is non existant, so I added about 1/2 the reccommended amount for my volume of water. I've got one of the return jets pointed upwards, the one by the steps in hopes this will raise the pH.

    Any other suggestions? I'm confident I can clear the water, but I want the system stablized. It's a vinyl pool with a sand filter, drawing water through the skimmer and bottom drain, returning through 3 jets.


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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD
    Welcome to TFP!

    It is uncommon for PH to be that low when TA is that high, but it isn't impossible. You don't want the pool to spend too much time with the PH below 7.0 as there can be damage to the vinyl liner. Aeration ought to raise the PH fairly quickly, but it it doesn't get above 7.0 fairly quickly you should help it along with a little borax, but just up to 7.0 and then use aeration to raise it further from there.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida
    Adding to what Jason suggested, it sounds like your running your chlorine too low. It sounds like you still have organics in your pool and you need more FC to clear them out and to rid yourself of the cc's that should be less than 1.0ppm.

    I'm not certain what your target ppm was for CYA, but I would suggest putting in enough chlorine to raise your total to about 15-18ppm and holding it at that level by testing and readding as often as possible. That shock level will kill of the remaining algae and clear the pool of cc's (almost).

    In sequence, get your pH up to 7.0 then work on your chlorine and your pool will sparkle.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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