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Thread: Concrete pool erosion or algae or both!!

  1. Back To Top    #1

    Join Date
    Jun 2016
    San Anselmo, CA

    Concrete pool erosion or algae or both!!

    Hi! I would really like to get an opinion on my pool surfaces; at first I thought it was purely old pool concrete erosion, bleeding toes etc... but now I am freaking out that I have a massive algae attack! Help.

    Concrete pool built 2002 (I think?)
    30' x 18' x 8' (+/- 15,000 gl)
    Caretaker pop ups x8
    Solar panels
    Venturi filter on main drain
    Northern California - lots of sunlight
    82 - 84 F

    I rebuilt caretaker system 6 months ago and erosion seams to be accelerating.

    Water has no visible cloudiness, seems nice and clear.
    The brown and black algae looking stuff is impervious to a wire brush.
    I recently became aware that my SWG performance was very poor FC 0.4 ppm 0 CYA (Yes I know - I am learning!!) and started to get a green ring on the tiles (since disappeared after shock).

    I have recently taken action upon reading this website and done the SLAM and I have CYA ordered.

    I would really like to get the benefit of some experienced eyes on the pool. Apart from the bottom of the pool the water looks great and clear in the sunlight, CC almost non existent. Many thanks!!


    pH 7.8
    FC 0.4
    CC 0.2
    TA 80 ppm
    CH 250 ppm
    SI 0.2
    CYA 0 ppm

    Added 1/4 gl HCl
    5 scoops powder Cl (Dichlor?)



    pH 7.4
    FC 16ppm
    CC 0 ppm trace

    8:00 pm
    pH 7.2
    FC 15ppm
    SWG running


    pH 7.4
    FC 14 ppm
    CC 0ppm

    7 pm
    SWG running all day
    pH 7.2
    FC 13.5 ppm

    9 am FC 11.5 ppm

    7 pm
    SWG running
    FC 10.5 ppm
    CC trace 0.2 ppm
    pH 7.4

  2. Back To Top    #2
    Mod Squad YippeeSkippy's Avatar
    Join Date
    Jan 2012
    'burbs of Augusta, Georgia

    Re: Concrete pool erosion or algae or both!!

    Go get a cheap bottle of Vitamin C tablets and put a mess of them in a sock and rub it on the surface of some of that staining. Does it remove it? If so you have metal stains.

    Then in another spot of stain try rubbing it with a chlorine puck (you can buy them individually) and see if that removes it? If so, its organic.

    When are you going to get that CYA in there??? Until then you're just sacrificing your FC to the Sun Gods and they are very greedy....
    Maddie :) 12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
    Our pool build--> Our Pool Solved Our Sloping Yard Skippy's Cheap Pool Cooler -->Skippy's New Fountain

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