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Thread: me vs them

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    me vs them

    New pool store opened up advertising their brand-new-state-of-the-art WaterLink DataMate 10 water analyzer "accurate to 1/100th of a part per million".
    I like numbers, so I figured why not have them test my water just to see if I'm interpreting my tests correctly. I mean pink or more pink or an in between shade of pink - it's all still very pink.

    So I took a sample from below pool surface at dusk last night and let it sit in my kitchen overnight. I tested the water then took the same sample to the pool store. I'm using the Taylor K1005 test.

    My FC looks like maybe a 3 or 4. They say 3.13 ppm. So far so good (except I do need to bump up the run time of my swg.)

    My TC? Eh. I don't think it got any more pink but maybe. They say 3.38 for a CC of .25

    pH - 7.4 vs 7.4 (swg should bring that up closer to 7.6 by the end of the week)

    "Hardness". I get CH of 120. The get "hardness" of 169. Idk what they are testing for though really.

    TA. Swirling swirling swirling. My green goes to clear at 6 drops, faint purple at 7 drops, and undeniably pink at 8 drops. They say my "alkalinity" is 48.2 ppm.

    CYA - I'm out of reagent but it's consistently been 70-80 ppm for me over the past two weeks. They say 106 ppm. [Maybe we should talk about what it means when the black dot disappears.]

    Copper I don't test for; they say 0.4ppm
    Iron I don't test for; they say 0.1ppm

    Salt. My aquacheck sticks are in between 3500 and 3800. They say 4200.

    I was in an admittedly bad mood stopping in on my lunch break and running late. The teen girl at the counter said I need to drain half the pool and refill to get my CYA down to 40. I said a CYA of 40 might be the goal for a pool using chlorine tabs but a SWG should be higher. She got kinda snippy with me [my perspective] and said she couldn't advise on any of the other numbers until I got my CYA down to 40 and retested.

    So.
    TA of 60-70-80? How do you interpret the titration colors?
    Am I reading CYA too strictly? I look at the chamber through one eye like using a monocular microscope - focus through left eye but no squinting the right one. I add the solution until I can't see the edges of the black dot in the chamber. I don't go until the chamber looks solid white, but just until I'm not able to distinguish the black dot.
    I don't know how they are determining salt. That discrepancy just doesn't make any sense. My numbers match exactly what pool calculator said they should be.
    26900 gal IG Vinyl (18'x36', 3' shallow end and 8' deep end plus steps)
    sand filter and 2.7hp variable speed timer
    Jandy Ei SWG (2yr old)

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    linen's Avatar
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    Re: me vs them

    First don't trust the pool store measurements...no matter how fancy and "expensive" their equipment is, we see time and time again bad results. And 1/100 of a ppm "accuracy" (I guess it is really resolution) is just ludicrous. Even if is it that good, what is being tested does not warrant that resolution. The tool not appropriately speced for the job.

    Quote Originally Posted by keep-it-simple
    So I took a sample from below pool surface at dusk last night and let it sit in my kitchen overnight. I tested the water then took the same sample to the pool store. I'm using the Taylor K1005 test.
    You should not hold onto a sample that long before testing...especially for FC, CC.

    Quote Originally Posted by keep-it-simple
    "Hardness". I get CH of 120. The get "hardness" of 169. Idk what they are testing for though really.
    It is likely they are including Magnesium hardness, which is generally not important. CH is what you want...ignore them.

    Quote Originally Posted by keep-it-simple
    TA. Swirling swirling swirling. My green goes to clear at 6 drops, faint purple at 7 drops, and undeniably pink at 8 drops. They say my "alkalinity" is 48.2 ppm.
    I'd trust yours.

    Quote Originally Posted by keep-it-simple
    CYA - I'm out of reagent but it's consistently been 70-80 ppm for me over the past two weeks. They say 106 ppm. [Maybe we should talk about what it means when the black dot disappears.]
    Make sure you do this test with sun at your back and tube held at waist level. See:
    http://www.troublefreepool.com/exten...1.html#p206397

    Quote Originally Posted by keep-it-simple
    That discrepancy just doesn't make any sense.
    Pool store testing often makes no sense.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Smykowski's Avatar
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    Re: me vs them

    I vote for never going to a pool store for chemistry advice ever again.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

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    duraleigh's Avatar
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    Re: me vs them

    "accurate to 1/100th of a part per million"
    for pool work is like buying a scale to weigh yourself in 1/000 of a pound increments. What's the point?

    Secondly it is absurdly false that they can measure (with validity) that accurately anyway.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: me vs them

    Quote Originally Posted by linen
    You should not hold onto a sample that long before testing...especially for FC, CC.
    Ok, good to know. I tested chlorine just now with my OTO and got the same reading.

    Thanks for your reply.
    I was really

    26900 gal IG Vinyl (18'x36', 3' shallow end and 8' deep end plus steps)
    sand filter and 2.7hp variable speed timer
    Jandy Ei SWG (2yr old)

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    Re: me vs them

    Quote Originally Posted by duraleigh
    What's the point?
    The point was to know which shade of pink is currently pink.
    But I agree, there is a level of absurdity there. I only estimate how much I weigh within 5lbs...
    26900 gal IG Vinyl (18'x36', 3' shallow end and 8' deep end plus steps)
    sand filter and 2.7hp variable speed timer
    Jandy Ei SWG (2yr old)

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    thehowheels's Avatar
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    Re: me vs them

    Quote Originally Posted by keep-it-simple
    I'm using the Taylor K1005 test.
    I'd recommend upgrading your kit to be able to perform the FAS-DPD chlorine test. It is by far more accurate and easy to read the results with titration compared to matching colors with the DPD test.

    And if you want accuracy, FAS-DPD can measure FC and CC to the nearest 0.2 PPM.
    Matt
    9k gallon, plaster, IG. Raised spa w/ spillover into pool. AO Smith Century Centurion / Purex Triton WisperFlo 0.5 HP, Hayward 1.5 HP (spa), Polaris 1-516-01 1.5 HP (blower). Hayward DE3620 36 ft2 72 GPM DE Filter, Polaris 145 cleaner. Pool built ~1980.
    Trouble-free, BBB since: April 25, 2013

  8. Back To Top    #8

    Re: me vs them

    Quote Originally Posted by keep-it-simple
    The teen girl at the counter said I need to drain half the pool and refill to get my CYA down to 40.
    I've never heard of a pool store advising a partial drain to lower CYA.

    +1 for getting FAS-DPD kit.
    Aaron
    [ Vogue Vectra 24' AG | Hard plumb: Hayward Power-Flo Matrix 1HP 2-speed, 27" sand filter & Pentair MiniMax 100 NG | Taylor K-2006 | Central IL ]
    Powered by: TFP, PoolMath & TFTestkits

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    harleysilo's Avatar
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    Re: me vs them

    Next time bring in two identical water samples and see what happens......
    18'x43' Sport Pool
    19,000 Gallons Vinyl Liner 3'-3.5'-4'
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    Test Kits - Pool Calculator - Chlorine/CYA Chart - Pool School

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  10. Back To Top    #10

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    Re: me vs them

    Quote Originally Posted by harleysilo
    Next time bring in two identical water samples and see what happens......
    Ha! I considered that. Or just tap water...
    26900 gal IG Vinyl (18'x36', 3' shallow end and 8' deep end plus steps)
    sand filter and 2.7hp variable speed timer
    Jandy Ei SWG (2yr old)

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