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Thread: strange FC test happenings

  1. Back To Top    #1
    mariane's Avatar
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    May 2012
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    strange FC test happenings

    I was testing the pool water today to get base levels.
    To set the stage: We have not yet taken off the winter cover, not circulated the water, nor added any chemicals since the fall closing. Ordered and received new FAS/DPD test regents. The water temp is 60 degrees near the surface.

    When testing for FC, the water sample stayed clear to slight gray in color after mixing in heaping test spoon of R-0870 DPD powder. Just for kicks I added the R-0003 reagent and the water turned pink after the first drop and remained pink for at least 60 drops till I gave up trying.
    I tested FC using the Basic test kit and FC measured 0.5. Just as I figured, basically no chlorine.
    I started over with the water sample and DPD powder and same slight gray color. Just for kicks, I added 1 drop of R-0003 to get the color pink and then added drops of R-0871. It took 5 drops to turn clear, meaning 2.5.
    I also tried it this time with: water sample, powder, then 5 drops R-0003 reagent and then it only took 1 drop of R-0871 to turn the sample clear.
    Obviously something is not right.

    Any thoughts?
    I know the FC test results with FAS/DPD will not effect my course of action but I'm just curious what might be happening.
    I will be shocking the pool upon opening because the water is clear but slightly green in color and there are dark powdery looking piles on the bottom, which I'm sure are algae since I have seen them before and that's what it was.

    Other results for those interested:
    pH - 7.2, TA - 30, CH -40, CYA - somewhere btwn 30 and 40, Borates - 0-15, Salts - 660.
    16 x 28 Doughboy Mystic Garden AGP with 7' deep end (used expandable vinyl liner) ~11,800 gals. Deep end main drain. Thru-the-wall skimmer, one return at deep end. Media Master 150# sand filter. Doughboy PowerPak II pump, 1 hp. Pentair MinimaxCH 150m natural gas heater. Polaris 65 when it feels like working . TF-100 test kit. No longer 'pool stored' 5 years and counting. In sunny but fickle metro-Detroit.

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    Mod Squad JohnT's Avatar
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    Re: strange FC test happenings

    I'd say it's telling you that you have no FC but some CC. Were the 60 drops you added R-003 or R-0871? You add 10 drops of R-003 and then go back to the 871 to measure CC.
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  3. Back To Top    #3
    mariane's Avatar
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    Re: strange FC test happenings

    OOPS!
    I added R-0003 60 drops, not R-0871.
    Thanks for setting me straight JohnT.

    I redid the test for FC then CC, this time doing it right. What happened this time was: slight gray color after powder, 1 drop R-0871 to return to clear. 0.5 FC. Added 10 drops R-0003, turned gray as before, added 20+ drops R-0871 with no change so I gave up. Therefore, who knows how much CC is there. Probably none either.
    None of the above turned pink.

    Or when testing for CC, am I supposed to start with a fresh sample and dump out the sample I just tested for FC?
    16 x 28 Doughboy Mystic Garden AGP with 7' deep end (used expandable vinyl liner) ~11,800 gals. Deep end main drain. Thru-the-wall skimmer, one return at deep end. Media Master 150# sand filter. Doughboy PowerPak II pump, 1 hp. Pentair MinimaxCH 150m natural gas heater. Polaris 65 when it feels like working . TF-100 test kit. No longer 'pool stored' 5 years and counting. In sunny but fickle metro-Detroit.

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