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Thread: is this black algae?

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    is this black algae?

    [attachment=2:4eel1c0y]pool1.jpg[/attachment:4eel1c0y][attachment=1:4eel1c0y]pool2.jpg[/attachment:4eel1c0y]
    this is my first pool. pool is gunite and wasn't open for 2 years. I started on saturday first using shock and then bleach and a bottle of natural chemistry first aid. I skipped mon and tues because of rain. I'm using a wire brush and it seems to be working a little. is this stained and would have to be acid washed? are there any tricks I can try to get the bottom of pool clean? or is this just a long process of shock nad scrub? 2 of the pictures are the stairs so you can see stain other picture is worse part of pool. will post more pictures if that is helpful. my fc this morning was 4 my ch is low
    the pf is 7.8.any help would be appreciated
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    32000 gal , gunite pool, de filter weber gensis and tiki bar

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    Richard320's Avatar
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    Re: is this black algae?

    No, it just looks like Calcium Scale. I'm sort of an expert on that, since my pool had a nice even coating of it.

    Black algae will look like polka dots, very dark green or black.

    Try pushing your pH down to 7.2. That helps dissolve it back into solution. It will still need brushing with a wire brush. For a year or more. If you're in a hurry, then a drain and an acid wash or sandblasting.
    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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    Melt In The Sun's Avatar
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    Re: is this black algae?

    All I can see is the shadow of a guy holding a camera
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
    TF Test Kits -- PoolMath -- Pool School
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    Re: is this black algae?

    thanks. l gonna keep scrubbing and if i have to will try acid as last resort. why does shocking the pool seem to be working? it seems to get a little bit of the stain off each time I did it.
    32000 gal , gunite pool, de filter weber gensis and tiki bar

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    Re: is this black algae?

    It may be that there is some organic stuff mixed in with the scale and the chlorine is removing the organic stuff. It is also possible it is completely organic (although I agree with Richard, it sure looks like scale)

    Test a spot by holding a tri-chlor puck on it for a couple of minutes. If it is gone completely, you can simply elevate your chlorine to shock level and keep it there until the stain is gone.

    For that matter, you can do that anyway and see how much improvement you get.

    If so, you need to read the article in Pool School, "How to Shock your Pool".....it doesn't sound like you are doing it correctly.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: is this black algae?

    if i do a no drain acid wash. is it ok to let the water/acid run thru my heater. I've read so many post on this site, I'm confusing myself. I thought I read one that said it would ruin heater, but i don't see a choice in the way my filter is set up, the water runs thru heater if it is off or on.
    32000 gal , gunite pool, de filter weber gensis and tiki bar

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    Re: is this black algae?

    You will need to bypass your heater. Low pH is a no-no for heaters.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: is this black algae?

    Quote Originally Posted by Melt In The Sun
    All I can see is the shadow of a guy holding a camera
    If I squint one eye I can see Elvis
    38,000 gal. IG gunite pool -- 20 x 40
    Pentair IntelliFlow VS Pump
    Pentair FNS 48 sf DE Filter
    Sand Shark suction side cleaner

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    Re: is this black algae?

    ph is down to 7.2 and the scrubbing seems to be working. my cH is at 200, I would assume this is good because I want the calcium to come off the pool floor. but should I raise it to suggested levels from the pool caculator
    32000 gal , gunite pool, de filter weber gensis and tiki bar

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    Richard320's Avatar
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    Re: is this black algae?

    Quote Originally Posted by eddie1129
    ph is down to 7.2 and the scrubbing seems to be working. my cH is at 200, I would assume this is good because I want the calcium to come off the pool floor. but should I raise it to suggested levels from the pool caculator
    No, don't add any. Keep the pH at 7.2 and it will lift it off the floor, slooooooooowly.
    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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