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Thread: Beware false pH readings!

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    Beware false pH readings!

    Test was re-run and the aberrant reading was not observed. The earlier reading must have been due to a contaminated vial. ???
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    I just bought a Taylor K-2006 test kit. I got a shock this morning when I tested my pH. I got a very acidic reading, which did not make any sense because I had checked the pH after refilling the pool and had added nothing but chlorine that could affect the pH reading. I had an older test kit on hand that contained a chlorine neutralizer reagent. I tested with the old test kit using the neutralizer and sure enough, the pH was right on the money, 7.5. I then read the Taylor test kit book. It advises against using the neutralizer and says their reagents contain the chlorine neutralizer and no additional neutralizer is needed. I used a drop of the neutralizer from the other test kit and reran the numbers with the Taylor, and sure enough ... the Taylor kit gave 7.5.

    My chlorine level is about 5 ppm (CYA around 50). This is apparently enough to overwhelm the chlorine neutralizer in the Taylor reagent.

    Beware! You may wind up trying to balance your pH to a false number!
    In-ground plaster pool, ~18,500 gal, Hayward single-speed pump, Pentair 60 sq. ft. DE filter, Polaris 280 robotic cleaner, SPA, heater (seldom used), use Taylor K2006 series test kit

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    Mod Squad jblizzle's Avatar
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    Re: Beware false pH readings!

    This does not make sense. The pH test reads artificially high when the FC is high (not low like you state), usually the test is off when the FC > 10ppm
    Jason, TFP Moderator
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    Mod Squad Bama Rambler's Avatar
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    Re: Beware false pH readings!

    What did the base demand test in the K-2006 kit tell you?
    Dave J. TFP Moderator
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    Richard320's Avatar
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    Re: Beware false pH readings!

    What does the FAS-DPD test say is your FC reading?

    If you're relying on just the OTO test, I find anything from 4-7 looks like 5, and even as high as 10 only looks a little off, schoolbus yellow more than canary yellow.

    If you got the FC reading from the DPD test - pink color matching - be aware that it can bleach out and give a false low FC reading.

    Maybe you're at 15, the DPD bleached out so you see 5ish, and the pH test went nuts?

    The pH test uses shades of color, not intensity. SOmetimes, for whatever reason, it looks pale. I add another drop of pH reagent and the color gets more intense without changing hue.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    Re: Beware false pH readings!

    OK. I reran this test and it came out right without the chlorine neutralizer. I must have had a contaminated vial before. ?? I will remove or edit this post immediately. Sorry, guys.

    FC = 4 ppm. It was 5 earlier today
    In-ground plaster pool, ~18,500 gal, Hayward single-speed pump, Pentair 60 sq. ft. DE filter, Polaris 280 robotic cleaner, SPA, heater (seldom used), use Taylor K2006 series test kit

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