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Thread: Black gunk at water line between tiles...

  1. Back To Top    #1

    Join Date
    May 2014
    Location
    Mesa, Arizona
    Posts
    180

    Black gunk at water line between tiles...

    ...right in the grout lines. It brushes off easily, even rubbing with my fingers gets it off. Wife just looks at me with a disgusting look as I brush it off saying, "it's just going to come back like it always has"!

    I inherited this pool when I remarried. So, for three years she's been giving me the evil eye when I brush the waterline off. And she's right, it does come back within days. Since finding this site, I've learned so much. Now I just need to know what I'm dealing with here. Latest pool readings are from yesterday morning as I've not had a chance to test since then because I was putting salt in to get those numbers up and didn't get up before sun up.

    FC-5
    CC-0.0
    PH-7.5
    CH-300
    TA-110
    CYA-80
    Salt-3200

    Pool is clear as all get out. The black line does not continue on the wall of pebbletec, just the grout between the tiles along waterline and some of the tiles have just a little bit of black gunk extending from the grout onto them as well but for the most part, it's really concentrated on the grout.

    What do I have here? Is this black algae?
    IG Pebbletec Blue Tahoe; Paddock Pool PCC 2000 pop-up; 22,275 gal 32' x 16' Diving with Auto-Fill
    Pentair 420 Cartridge filter; 3 hp VS Whisperflo Main Drain, 1 1/2 hp Whisperflo Running Pop-Ups; Jandy AquaPure 1400
    1 1/2 Whisperflo dedicated to Rock Waterfall; TF-100; Taylor K-1766; Pool Built in 1997

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    Location
    San Dimas, CA (LA County)
    Posts
    18,768

    Re: Black gunk at water line between tiles...

    It's probably just plain algae. Get an empty windex bottle or something and fill it with bleach. Scrub the stuff with a plastic brush - a nail brush, carwash brush, whatever - and rinse it with straight bleach. Do that for a couple days and it should stay gone.
    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!

  3. Back To Top    #3

    Join Date
    May 2014
    Location
    Mesa, Arizona
    Posts
    180

    Re: Black gunk at water line between tiles...

    Good deal Richard, thanks for the quick reply. Off topic here, but do you live on this site? You're so quick to answer almost every thread with your very knowledgeable mind!
    IG Pebbletec Blue Tahoe; Paddock Pool PCC 2000 pop-up; 22,275 gal 32' x 16' Diving with Auto-Fill
    Pentair 420 Cartridge filter; 3 hp VS Whisperflo Main Drain, 1 1/2 hp Whisperflo Running Pop-Ups; Jandy AquaPure 1400
    1 1/2 Whisperflo dedicated to Rock Waterfall; TF-100; Taylor K-1766; Pool Built in 1997

  4. Back To Top    #4
    Richard320's Avatar
    Join Date
    Jan 2010
    Location
    San Dimas, CA (LA County)
    Posts
    18,768

    Re: Black gunk at water line between tiles...

    I sit at a desk and i'm bored a lot. Sometimes I've off for two or three hours at a time!
    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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