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Thread: Bright Red on ph test

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    Bright Red on ph test

    had a lot of rain here lately, 10 inches this week. Having problems getting a good ph reading. When I add 2 drops regent the tube turns bright red. So I used a 10 ml tube, turns red at 4 drops.
    Chlorine is at 6
    CYA 50
    Aly. 110

    can the ph really be that high? or it really low and not reading correctly?

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD
    You normally only have a problem with the PH test when FC is above 10. Since your chlorine is only 6 the test should be acurate.

    Rain aerates the pool, which can sometimes cause the PH to rise.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Join Date
    Mar 2007
    San Rafael, CA USA
    Are you sure you are doing the pH test instead of the Total Alkalinity (TA) test? You don't count drops and have something turn red after so many drops with the pH test. The pH test is normally adding 5 drops of an indicator and comparing the color. The TA test is the one where you first add a couple drops of thiosulfate, then 5 drops of indicator, and then count the drops of titrant to have the sample go from turning green to red and this is usually done with the 25 ml sample size. I'm confused by your test.
    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
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  4. Back To Top    #4
    I am performing the color indicator test (5 drops) - just that the color goes off the scale with 5 drops into the color comparator tube. alkaylinity and chlorine test normal.

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    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida
    Turns bright red or purple? Sounds like your pH is very high or your testing chemistry is a little old. Easy to buy another pH test kit ($6.00) and check your results.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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  6. Back To Top    #6
    Looks like the indicator was correct. I added 64 oz. of acid - the ph dropped down to 7.3.
    all looks good now.

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