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Thread: Does High FC Throw Off pH Numbers?

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    wjaneala's Avatar
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    Does High FC Throw Off pH Numbers?

    So, I decided to do a SLAM since it seems like I have algae creeping back every time I think it's gone. Since the other day when I ran the auto cleaner to get rid of what I thought was dirt/pollen on the entire surface of the pool, my deep end is now green. I really thought I had this beat, but I guess not. Anyway, I've raised my FC up to my shock level of 24, and it's holding right now. Just for kicks, I checked the pH, and it was at least 8.2. Is that just because of the shock level? Or do I have a bigger problem?

    FC 24
    CC .5
    CYA 60
    pH 8.2
    CH 200
    Wendy
    1980s 20x40 in-ground beast, 36K gallons, 4' - 8', vinyl liner, Sand Dollar sand filter, two skimmers, bottom drain, three returns
    TF-100 Test Kit

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    Mod Squad jblizzle's Avatar
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    Re: Does High FC Throw Off pH Numbers?

    Yes. The pH test is not accurate (reads a false high) when the FC > 10ppm.
    This is why the first step of the SLAM process is to lower the pH to 7.2-7.4
    Jason, TFP Moderator
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    wjaneala's Avatar
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    Re: Does High FC Throw Off pH Numbers?

    Thanks, Jason. So here's an odd question..I'm doing the SLAM, maintaining the 24 FC right now. I've been brushing the cr*p out of the pool, but I can't reach the middle of the bottom of the deep end with my brush. I'd say there's a a good 18 inch perimeter around the bottom drain that I can't reach. Is that going to cause the SLAM not to work?
    Wendy
    1980s 20x40 in-ground beast, 36K gallons, 4' - 8', vinyl liner, Sand Dollar sand filter, two skimmers, bottom drain, three returns
    TF-100 Test Kit

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    Mod Squad pooldv's Avatar
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    Re: Does High FC Throw Off pH Numbers?

    It could make the SLAM take longer and/or use more chlorine. Brushing exposes the layers of algae to chlorine to kill it faster.
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    wjaneala's Avatar
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    Re: Does High FC Throw Off pH Numbers?

    I'm going to try lying on the diving board and leaning over as far as I can to see if I can get to it. This should be funny.
    Wendy
    1980s 20x40 in-ground beast, 36K gallons, 4' - 8', vinyl liner, Sand Dollar sand filter, two skimmers, bottom drain, three returns
    TF-100 Test Kit

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    Mod Squad jblizzle's Avatar
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    Re: Does High FC Throw Off pH Numbers?

    Sounds like you need a longer pole.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Does High FC Throw Off pH Numbers?

    Agreed that you need to get a longer pole. This will not only help with the slam, but with long term maintenance. You should brush your pool regularly, and if there is a large area you always miss, it might cause you some long term aggravation.
    IG W/Vinyl Liner Oval 18x40, 21K gal, Oval 3'-8'
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    Re: Does High FC Throw Off pH Numbers?

    duck tape a broom on to the pole.
    Bob - INTEX 12x24 owner, 'New to me' Kreepy Krauly Sand Shark, Test kit: TF-100 w/Speed Stir

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    wjaneala's Avatar
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    Re: Does High FC Throw Off pH Numbers?

    You all can order your "I'm with Stupid" t-shirts now, with the fingers pointed directly at me. I thought I had my pole extended as far as it would go, but it was only stuck. I got a good extra two feet on it today. w00t! NOW the entire pool has been brushed.
    Wendy
    1980s 20x40 in-ground beast, 36K gallons, 4' - 8', vinyl liner, Sand Dollar sand filter, two skimmers, bottom drain, three returns
    TF-100 Test Kit

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    Mod Squad pooldv's Avatar
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    Re: Does High FC Throw Off pH Numbers?

    Nice! Problem solved.
    TFP Moderator
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