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Thread: pH discrepancy in readings

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    pH discrepancy in readings

    1. I just recently found this site and ordered the TF 100 kit. My previous kit/testing consisted of the basic (chlorine/pH) the installer gave me. My pH readings have always shown higher than the pool store readings. I figured the TF 100 kit would help me get more accurate readings. My k1000 is still telling me I have 8.2 (or higher) pH. The last 2 pool store readings are below:
    6/20:
    TA 100
    pH 7.92
    CYA 40
    FC .79
    TC .84
    CH 250

    I increased SWG % to 35 and added 11 oz of MA. My k1000 test still showed bright pink (8.2 or higher). However the pool store showed:
    6/22:
    TA 100
    pH 7.80
    CYA 28
    FC 2.0
    TC 2.0
    CH 250

    My salt readings have been 3000 (according to my aquapod); the store readings have always been lower (2900/2800).

    2. My test kit readings were much higher than store's:
    TA 320 (using the 10ml method; 425 doing the 15 ml method)
    CYA 30, maybe 32, when store read 40)

    When I asked, he said his readings use lasers (i.e. more accurate than test kits...) I don't trust my readings yet, doing them only once (but following the rec of wiping w wet cloth after each drop for static electricity - takes a long time...!)

    Any suggestions/reccomendations, please? Thanks much
    near Pensacola, FL installed fall 2011; 12,800 gal IG plaster; Pump = Hayward Ecostar model SP3400VSP with Hayward SwimClear cartridge filter model # C3030 (effective filtration rate 325 FT squared/122 GPM design flow rate); SWG= Hayward Aqua Plus with Aqua Pod remote control; Polaris 280 on separate boost pump

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    frustratedpoolmom's Avatar
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    Re: pH discrepancy in readings

    Use the wet cloth - yes takes a long time but necessary with a new kit.

    Test your Tap water - is it high in TA? (stick with the 25ml sample water)

    I trust your readings - if you are calculating correctly if the TA is as high as you tested that makes sense that the PH didn't budge. IF your TA is very high it's gonna take more than 11oz of MA to lower the PH.
    Helpful links: Pool School; CYA/Chlorine Chart
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    Re: pH discrepancy in readings

    I just pictured dolphins with lasers on their head, and heard Austin Powers talking to me.

    I would trust your own tests and eyes. Be sure you hold the testing block up to something white when checking the color. I use my skimmer lid. If you hold it up to the sky or toward your pool, it makes it harder to get an accurate color reading.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    Richard320's Avatar
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    Re: pH discrepancy in readings

    Welcome!

    Trust your own readings. Make sure you have a white background. I find it better to hold the tester at arm's length.

    inconsistency-in-readings-t61728.html
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    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: pH discrepancy in readings

    thanks for quick response. Hoping I'll get better with practice. Sorry for the deluge of questions...

    1. I couldn't find via site search... is there a discussion of whether or not and how long you should turn off the SWG with which chemicals (and best method to apply... in skimmer/broadcast to deep end, etc.)?

    2. In testing the TA, drop #15 turned clear; drop #16 turned ever so slight purple; drop #17 turned pinkish, so would my TA be 150 or 170? Is reagent R-0009 (for the TA) the only one I need to wipe with wet paper towel after each drop? Don't need to for FC, CYA, CH, etc?

    3. last pool store readings of CA have been 250, the second one I just measured reads 400 (using 25 ml sample). From what I've read, danger of high calcium is scaling? Will that be a white line or stain at water's edge? I have neither (and water is clear), trying to confirm what to look for and how do I lower calcium if it becomes a problem? I measured tap water at CH of 90.

    4. In answer to one of the reply questions, my tap water CYA was 0 (or below 20) - it was clear to the top of the tube - I did not try cut it with distilled water.

    5. Next step? should I work toward getting CYA (pool store 28 / my reading 32) toward 70 first, then TA towards 100 ?
    near Pensacola, FL installed fall 2011; 12,800 gal IG plaster; Pump = Hayward Ecostar model SP3400VSP with Hayward SwimClear cartridge filter model # C3030 (effective filtration rate 325 FT squared/122 GPM design flow rate); SWG= Hayward Aqua Plus with Aqua Pod remote control; Polaris 280 on separate boost pump

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    Re: pH discrepancy in readings

    1. Don't run SWG when adding salt. You'll need to dissolve the salt for 24 hours before turning on the SWG. You should not put any chemicals in your skimmer. It sends a concentrated form of the chemical to the equipment. Specific instructions can be provided, but in general add things slowly near the return. Powder CYA can be hung inside a sock in front of the skimmer.

    2. This link will help you with your testing. extended-test-kit-directions-t25081.html

    3. Keep an eye on your pH and TA and you are OK, even at 400. The only way to lower calcium is to drain and refill. Reverse osmosis is another option, but isn't available everywhere and can be expensive.

    4. Tap water will always have 0 CYA. Did you mean TA?

    5. You can adjust CYA and TA at the same time. I recommend trying for more like 80 for your TA.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    Mod Squad jblizzle's Avatar
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    Re: pH discrepancy in readings

    Quote Originally Posted by RobbieH
    I just pictured dolphins with lasers on their head, and heard Austin Powers talking to me.
    I was thinking the same thing

    they use LASERS so of course the test is better
    Jason, TFP Moderator
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    Re: pH discrepancy in readings

    ok - thanks. When adding CYA, is liquid or dry preferred / any different? Do I turn off SWG (and if so how long?) and keep pump on for "x"? Same ? for adding MA - turn off SWG how long and keep pump on how long?
    near Pensacola, FL installed fall 2011; 12,800 gal IG plaster; Pump = Hayward Ecostar model SP3400VSP with Hayward SwimClear cartridge filter model # C3030 (effective filtration rate 325 FT squared/122 GPM design flow rate); SWG= Hayward Aqua Plus with Aqua Pod remote control; Polaris 280 on separate boost pump

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    Richard320's Avatar
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    Re: pH discrepancy in readings

    Quote Originally Posted by Lisa M
    ok - thanks. When adding CYA, is liquid or dry preferred / any different? Do I turn off SWG (and if so how long?) and keep pump on for "x"? Same ? for adding MA - turn off SWG how long and keep pump on how long?
    Either works. Dry is cheaper but takes a while to dissolve. You need not turn things off. Pour liquids into the return stream so they disperse quickly. Granular CYA gets tied up in a sock or nylon and hung in front of the return or dangled from a floating pool toy. Don;t pour it into the skimmer!
    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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    Mod Squad Bama Rambler's Avatar
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    Re: pH discrepancy in readings

    We mostly recommend granular (dry) CYA just because of the cost of liquid being so high and there's almost never a rush to get CYA in the pool.

    The only thing you really need to shut the swg off for when adding is salt. Anything else and it's fine to leave it running.
    Dave J. TFP Moderator
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