Become a TFP Supporter Pool Math Forum Rules Pool School
Page 1 of 2 12 LastLast
Results 1 to 20 of 22

Thread: Strange PH readings

  1. Back To Top    #1
    simonmoll's Avatar
    Join Date
    Feb 2014
    Location
    Barbados
    Posts
    52

    Strange PH readings

    I have been using TFP for a couple of years now and have not had a green pool for a long time .
    All I do is use a Taylor 100 kit and test for chlorine and PH every morning and add bleach acid as needed. Very occasionally I do a full test but all it tells me is what I already know!
    However something funny happened the other day.

    I looked at the PH and it was high around 8-8.2+. So I shook the tester violently and the PH went to 7.2.
    I tried this a few times over the next few days and the same happened. But not today it showed 7.6 and stayed there after vigorous shaking so I am completely flummoxed!

    I am sure all is ok just wondered if anyone else had had this happen and whether a vigorous shake rather than a couple of flicks of the wrist is really needed?
    11,750 gall. concrete, in ground pool in Barbados. Shallow (max depth 4'6"). New (May 2016) Hayward variable speed pump and SWG and (make?) PH controller. Hayward Star Clear filter (50 sq ft). History of algae but not since joining TFP! Surrounded by coconut trees and other palms. Serious white fly infestation of palms continues.

  2. Back To Top    #2
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Location
    Tucson, AZ
    Posts
    11,620

    Re: Strange PH readings

    Quote Originally Posted by simonmoll View Post
    I have been using TFP for a couple of years now and have not had a green pool for a long time .
    All I do is use a Taylor 100 kit and test for chlorine and PH every morning and add bleach acid as needed. Very occasionally I do a full test but all it tells me is what I already know!
    However something funny happened the other day.

    I looked at the PH and it was high around 8-8.2+. So I shook the tester violently and the PH went to 7.2.
    I tried this a few times over the next few days and the same happened. But not today it showed 7.6 and stayed there after vigorous shaking so I am completely flummoxed!

    I am sure all is ok just wondered if anyone else had had this happen and whether a vigorous shake rather than a couple of flicks of the wrist is really needed?
    What's your FC level at?


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  3. Back To Top    #3
    simonmoll's Avatar
    Join Date
    Feb 2014
    Location
    Barbados
    Posts
    52

    Re: Strange PH readings

    FC 5.5 CC zero
    11,750 gall. concrete, in ground pool in Barbados. Shallow (max depth 4'6"). New (May 2016) Hayward variable speed pump and SWG and (make?) PH controller. Hayward Star Clear filter (50 sq ft). History of algae but not since joining TFP! Surrounded by coconut trees and other palms. Serious white fly infestation of palms continues.

  4. Back To Top    #4
    simonmoll's Avatar
    Join Date
    Feb 2014
    Location
    Barbados
    Posts
    52

    Re: Strange PH readings

    FC 5.5
    CC 0.0
    PH 7.2 after vigorous shaking 8.2 before??
    TA 40
    CH 625
    CYA No reading (0.0) maybe the chemical has gone off?

    So am thinking it is low TA that may be causing this. Will sort that out and test again.
    11,750 gall. concrete, in ground pool in Barbados. Shallow (max depth 4'6"). New (May 2016) Hayward variable speed pump and SWG and (make?) PH controller. Hayward Star Clear filter (50 sq ft). History of algae but not since joining TFP! Surrounded by coconut trees and other palms. Serious white fly infestation of palms continues.

  5. Back To Top    #5
    Mod Squad kimkats's Avatar
    Join Date
    Jul 2012
    Location
    Tallahassee, FL
    Posts
    26,723

    Re: Strange PH readings

    How old are your regents?

    I LOVE your av picture! SO pretty!

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

  6. Back To Top    #6
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Location
    Tucson, AZ
    Posts
    11,620

    Re: Strange PH readings

    Quote Originally Posted by simonmoll View Post
    FC 5.5
    CC 0.0
    PH 7.2 after vigorous shaking 8.2 before??
    TA 40
    CH 625
    CYA No reading (0.0) maybe the chemical has gone off?

    So am thinking it is low TA that may be causing this. Will sort that out and test again.
    It's not your TA that's the problem. Mine is nearly just as low as your TA and I tried replicating your problem. No amount of vigorous shaking changes the color of my pH test at all.

    You are also showing a CYA of 0 which is really only possible on a fresh fill. Otherwise, if it's low, it's just less than 30ppm as that's the lowest possible reading for the test. A low CYA is not good as that makes your 5.5 ppm FC very harsh.

    If your reagents are old, I'd suggest new ones before you go balancing your water. Then, with new reagents in hand, get your water properly set to the recommended levels and see if the pH test still is a problem.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  7. Back To Top    #7

    Join Date
    Dec 2015
    Location
    arlington, tx
    Posts
    100

    Re: Strange PH readings

    this statement comes from Pool School - ABCs of Pool Water Chemistry

    TA - Total Alkalinity

    At low TA levels, the PH tends to swing around wildly.

  8. Back To Top    #8

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,084

    Re: Strange PH readings

    At low TA levels, the PH tends to swing around wildly.
    pH and TA are easily the most misunderstood and mysterious of the parameters we test....lots of misconceptions and assumptions that are not quite true.

    I don't think the collective forum experience demonstrates the statement above to be true. Changing it from "tends to" to "may" is probably better wording.

    Pool School will always be a work in progress and needs to be tweaked often to provide the most accurate information.

    All that said, I don't think that statement is relative to the thread, is it?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  9. Back To Top    #9

    Join Date
    Dec 2015
    Location
    arlington, tx
    Posts
    100

    Re: Strange PH readings

    Quote Originally Posted by duraleigh View Post
    pH and TA are easily the most misunderstood and mysterious of the parameters we test....lots of misconceptions and assumptions that are not quite true.
    I don't think the collective forum experience demonstrates the statement above to be true. Changing it from "tends to" to "may" is probably better wording.
    Pool School will always be a work in progress and needs to be tweaked often to provide the most accurate information.
    All that said, I don't think that statement is relative to the thread, is it?
    one person thinks low TA may be causing the wild TA swings, another person says no. i thought pool school, which everyone tells us to refer to, could help with this subject.

    pool school's message may not be correct (how am i to know?), but this messenger's heart was trying to help out.

    if pool school is wrong, then i hope it will be corrected.

  10. Back To Top    #10
    borjis's Avatar
    Join Date
    Aug 2014
    Location
    Pacific NW
    Posts
    2,058

    Re: Strange PH readings

    Every pool is different. Pool school is pretty darn close...close enough for most to learn
    how their pool reacts to chemical additions, but it can't be 100% accurate that would be impossible.

    Example:

    A lot of folks with plaster pools in the southern regions have ph rising, it's been found and
    recommended they could go as low as TA of 50 to help keep the ph steady. Pool math
    was even changed a few months back from that. A lot of plaster pool owners in
    the south are now not needing to add acid or much less than they had to before

    My vinyl lined pool on the other hand has constant falling PH if it is not at least
    at TA of 80. Any lower and my ph falls.
    16x32 IG Vinyl, 13,000 Gals. Hayward S-244T sand filter, SP2810X15 pump
    (1.5 HP motor) Raypak PR266AEN (266k btu) gas heater. TF-100 Test Kit.
    Dolphin E10 Cleaning Robot.

  11. Back To Top    #11
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Location
    Tucson, AZ
    Posts
    11,620

    Strange PH readings

    Let's not get too far afield here as this is turning into a wild goose chase post. The OP isn't describing a normal situation and has two confounding factors at play here.

    First, the reagents used are suspect in age. That alone can cause lots of issues.

    The second thing is the OP is doing something you should never do - namely, you should never, under any circumstance "vigorously shake" test solutions. None of the test procedures call for vigorous shaking. All test solutions should be inverted to mix. Two or three inversions is more than enough to fully mix the phenol red indicator.

    So while this may be an odd effect (that no one has since replicated) it is not really necessary to hash out possible explanations because (a) we don't know if the regents used are bad and/or (b) it's not all that unusual to expect to get odd results when you don't follow the test procedures properly.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  12. Back To Top    #12
    simonmoll's Avatar
    Join Date
    Feb 2014
    Location
    Barbados
    Posts
    52

    Re: Strange PH readings

    The Taylor 100 kit was bought in January through Amazon. PH reagent expiry 07/17 so that should not be an issue.
    Shaking vigorously or inverting two or three times: should that make a difference to the chemical reaction?

    It seems that when FC is low at the end of the (sunny) day that this effect does not happen.
    After writing that I went to test: not true.. FC=1 (was 5 same time yesterday) PH 8.2 + until shook vigorously then 7.2! (so don't know whether to add acid or not!!

    Anyway my CYA was <30. I said zero because there was virtually no cloudiness at 30. I am going to add stabaliser slowly and see what happens as I am using too much chlorine recently.
    Then will get TA to a higher level and see if that helps.
    11,750 gall. concrete, in ground pool in Barbados. Shallow (max depth 4'6"). New (May 2016) Hayward variable speed pump and SWG and (make?) PH controller. Hayward Star Clear filter (50 sq ft). History of algae but not since joining TFP! Surrounded by coconut trees and other palms. Serious white fly infestation of palms continues.

  13. Back To Top    #13

    Join Date
    Aug 2014
    Location
    Shallotte, NC
    Posts
    693

    Re: Strange PH readings

    Quote Originally Posted by simonmoll View Post
    The Taylor 100 kit was bought in January through Amazon. PH reagent expiry 07/17 so that should not be an issue.
    Can you recheck the part number of your kit? It sounds like a Taylor kit, but I would expect it to be 4 figures, not 3.... Like K-1007.... not K-100.

  14. Back To Top    #14
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Location
    Tucson, AZ
    Posts
    11,620

    Re: Strange PH readings

    Quote Originally Posted by simonmoll View Post
    Shaking vigorously or inverting two or three times: should that make a difference to the chemical reaction?
    The short answer to this is - YES, it is possible.

    Shaking the pool water sample vigorously can liberate both dissolved CO2 gas and, to a lesser extent, chlorine. However, both of those processes will generally cause pH to rise, not fall. Mind you, this is only possible in principle as i have not done any calculations to determine the magnitude of the change, it could be immeasurably small.

    One practical area where shaking would be ill advised is in the CYA test. You can entrain tiny air bubbles in the solution that can stick to the melamine precipitate and that can make the sample appear cloudier than it really is. This would lead to a false-high result.

    At the end of the day, the tests do not require vigorous shaking. Gentle inversion of the sample or hand swirling is more than adequate to mix the reagents. The chemical reactions generally happen very quickly and vigorous shaking will not make them go any faster. If mixing is an issue, one can always purchase a SpeedStir to help with the mixing process.

    So, if your reagents are still good, then add the five drops of R-0004 phenol red reagent, invert 2-3 times to mix and determine your pH. Shaking vigorously is not necessary.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  15. Back To Top    #15

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,084

    Re: Strange PH readings

    Big thanks to JoyfulNoise for keeping this thread on track. It is an issue that needs work on our good (but can be better) forum.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  16. Back To Top    #16
    simonmoll's Avatar
    Join Date
    Feb 2014
    Location
    Barbados
    Posts
    52

    Re: Strange PH readings

    Thanks for all your inputs.
    I will use the results from gentle shaking!
    11,750 gall. concrete, in ground pool in Barbados. Shallow (max depth 4'6"). New (May 2016) Hayward variable speed pump and SWG and (make?) PH controller. Hayward Star Clear filter (50 sq ft). History of algae but not since joining TFP! Surrounded by coconut trees and other palms. Serious white fly infestation of palms continues.

  17. Back To Top    #17

    TFP Guide
    Mr Bruce's Avatar
    Join Date
    Mar 2014
    Location
    Greenville, SC
    Posts
    1,798

    Re: Strange PH readings

    Quote Originally Posted by JoyfulNoise View Post
    One practical area where shaking would be ill advised is in the CYA test. You can entrain tiny air bubbles in the solution that can stick to the melamine precipitate and that can make the sample appear cloudier than it really is. This would lead to a false-high result.
    Looks like the Extended Test Kit Directions need to be updated:
    Cap and then shake the mixing bottle for 30 seconds.
    Which is what I've been doing for 2 years :/
    32K gallon Plaster - 1hp Hayward 2 speed Super Pump - Hayward S200 Sand Filter - TF100XL
    Test Kits - Pool Math - Chlorine/CYA/Target/Slam Chart

  18. Back To Top    #18
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Location
    Tucson, AZ
    Posts
    11,620

    Re: Strange PH readings

    That really should be better defined. The actual Taylor instructions say -

    2. Add R-0013 Cyanuric Acid Reagent to neck. Cap and mix for 30 seconds. Sample will turn cloudy if cyanuric acid is present.
    And by mix, they mean a gentle inversion mix (it's what most chemist-types would understand it to mean).

    I will talk to the mods about fixing that.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  19. Back To Top    #19

    In the Industry

    bdavis466's Avatar
    Join Date
    Aug 2014
    Location
    Riverside, CA
    Posts
    3,303

    Re: Strange PH readings

    I don't recall it mentioned, but I wonder with little to no cya in the water, a FC of 5.5 is extremely harsh and could very well be causing a false high reading of the pH test. Is this a possibility Matt?

    It is preached here that FC levels over 10 cause false high readings on the pH test but that should be much more dependent on the CYA level since a FC of 10 with 30ppm CYA is much more concentrated than 10 FC at 80ppm CYA?
    -Brian-
    33K Pool/Spa, Pentair Equipment
    POOL BUILD
    Davis Custom Construction - Home Page

  20. Back To Top    #20
    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    Location
    DFW, TX
    Posts
    23,999

    Re: Strange PH readings

    The TFTestkits.net instructions say Mix, then wait at least 30 seconds. Shake once more.
    TFP Moderator
    If TFP helped you or saved you money - Become a TFP Supporter! <--Click here
    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •