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Thread: Black Algae ...Pitting my problem?

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    Black Algae ...Pitting my problem?

    Hi, I have one year old plaster and see what I think is black algae. I will be shocking tomorrow. My question is this...
    1. Black algae is centered on rough spots in the pool...So is there a way to sand these rough spots down? It appears smooth but when you touch it, there is a bit of roughness. Just curious if this will continue to be a problem if I dont sand and I let the pool go in the winter.

    2. The other unrelated question is Where does everyone buy their pool cartridges? I have monster ones and would like a spare set to soak in solution while the other ones are in. Thanks!
    IG Gunnite Pool Size: 25K gallons (20 x 40, 3'6" to 6" depth) with 2 huge Baker Hydro cartridge filters under the skimmer baskets on the suction side, 2 mech timers
    BRAND NEW PLASTER! Quartzscapes/Diamondbrite, Newer Polaris 280, Brand New Hayward Maxflo VS, Brand New Pentair Intelichlor
    I will conquer the black algae this pool season!!!

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    Re: Black Algae ...Pitting my problem?

    I have the same problem where my plaster is in bad shape. Previous homeowner did not have any CH in my pool, and the plaster was applied in either 89 or 91, so I unfortunately have some very rough areas in my plaster. If you don't keep those areas well brushed, you can get black algae, even with proper pool balance. I use a wire brush on the end of my pool pole to keep these areas as well cleaned as possible. You will need to do the same while you are getting rid of the black algae, just shocking will not work.

    I don't know any way to fix the problem, you may need to call the pool builder.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    BoDarville's Avatar
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    Re: Black Algae ...Pitting my problem?

    With black algae, "elbow grease" is as much a key ingredient as is chlorine. Frequent brushing will expose the black algae to the elevated chlorine levels and prevent the algae from excreting waxy substances that inhibit chlorine being able to get at it. Suggest getting a stainless steel brush. As for chlorine, you need to keep it about 50% higher than the top end of the recommended range for your CYA as long as any black algae is present while brushing several times a day.
    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
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    Re: Black Algae ...Pitting my problem?

    So sanding it with diamond paper is not an option?
    IG Gunnite Pool Size: 25K gallons (20 x 40, 3'6" to 6" depth) with 2 huge Baker Hydro cartridge filters under the skimmer baskets on the suction side, 2 mech timers
    BRAND NEW PLASTER! Quartzscapes/Diamondbrite, Newer Polaris 280, Brand New Hayward Maxflo VS, Brand New Pentair Intelichlor
    I will conquer the black algae this pool season!!!

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    Re: Black Algae ...Pitting my problem?

    So the guy that just installed the SWG system on my pool said the our city water company has been adding phosphates to the city water and that it can affect the ability to control algae. That makes so much sense since we used to have a Whole house filtration unit (that was removed this winter after a line burst) that might have filtered out phosphate last year but this year for additions of pool water we were getting straight unfiltered water from the city.
    IG Gunnite Pool Size: 25K gallons (20 x 40, 3'6" to 6" depth) with 2 huge Baker Hydro cartridge filters under the skimmer baskets on the suction side, 2 mech timers
    BRAND NEW PLASTER! Quartzscapes/Diamondbrite, Newer Polaris 280, Brand New Hayward Maxflo VS, Brand New Pentair Intelichlor
    I will conquer the black algae this pool season!!!

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    Pool Putty for rough spots

    Im tired of the constant black algae....even after installing a SWG and getting rid of black algae with good readings on chems..the little spots pop up in a couple places. Can I put pool putty in the rough spots? Thats where these always are.
    IG Gunnite Pool Size: 25K gallons (20 x 40, 3'6" to 6" depth) with 2 huge Baker Hydro cartridge filters under the skimmer baskets on the suction side, 2 mech timers
    BRAND NEW PLASTER! Quartzscapes/Diamondbrite, Newer Polaris 280, Brand New Hayward Maxflo VS, Brand New Pentair Intelichlor
    I will conquer the black algae this pool season!!!

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    Re: Black Algae ...Pitting my problem?

    What is your CYA and FC level?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Black Algae ...Pitting my problem?

    From what I have read you will never be able to get rid of it completely. It has roots that take hold and grown dowbn into the plaster.
    20,000 gallon inground plaster
    1 HP Hayward Norrthstar
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    Built about 25-30 yrs. ago

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    Re: Black Algae ...Pitting my problem?

    Never? Really? I'm doomed? Does it still grow in cold weather?
    My Chlorine has been between 8-12 for the past week, with brushing and filter washing too. I'm about to go and rub chlorine pucks on it after brushing. Someone said to rub them on them before night and to let the pump rest and to let the chlorine sit on them overnight? This is very frustrating.
    IG Gunnite Pool Size: 25K gallons (20 x 40, 3'6" to 6" depth) with 2 huge Baker Hydro cartridge filters under the skimmer baskets on the suction side, 2 mech timers
    BRAND NEW PLASTER! Quartzscapes/Diamondbrite, Newer Polaris 280, Brand New Hayward Maxflo VS, Brand New Pentair Intelichlor
    I will conquer the black algae this pool season!!!

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    Melt In The Sun's Avatar
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    Re: Black Algae ...Pitting my problem?

    You certainly can get rid of it, but it takes diligence. You have to scrub it, as mentioned, and you have to keep the FC high while you do it and for a while after. As Duraleigh asked, what is your CYA level, and how are you testing?

    I much prefer a very small steel brush for this...about 1 inch by 1/2 inch, like you might use for cleaning paintbrushes. You certainly can smooth out the rough spots if you want...some medium grit wet/dry sandpaper will get the job done.
    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!
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    Re: Black Algae ...Pitting my problem?

    CYA is at 40...I know its low for SWG but I knew I had this prob and wanted to be able to go low with my Chlorine at 12 instead of ramping up CYA and having to go at a higher Chlorine level. I will get a little brush and attempt that route with the puck rubbing into the grooves afterwards. Will report any progress.
    IG Gunnite Pool Size: 25K gallons (20 x 40, 3'6" to 6" depth) with 2 huge Baker Hydro cartridge filters under the skimmer baskets on the suction side, 2 mech timers
    BRAND NEW PLASTER! Quartzscapes/Diamondbrite, Newer Polaris 280, Brand New Hayward Maxflo VS, Brand New Pentair Intelichlor
    I will conquer the black algae this pool season!!!

  12. Back To Top    #12

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    Re: Black Algae ...Pitting my problem?

    Quote Originally Posted by mrswhitsie
    So the guy that just installed the SWG system on my pool said the our city water company has been adding phosphates to the city water and that it can affect the ability to control algae.
    Phosphates are an essential nutrient for algae, but chlorine will kill algae faster than it can grow regardless of algae nutrient (phosphate, nitrate) level. We have one pool owner with tens of thousands of ppb phosphate and my own pool had over 3000 ppb phosphate in the past and others have had 5000 or more, but all have no algae because the proper FC is maintained relative to the CYA level. It is true, though, that with established algae, especially black algae, it will take a higher chlorine level and vigorous brushing to remove. As to whether it can be kept away, that depends on other factors that have been noted such as circulation, roughness of pool surface, etc. However, with your pool only one year old and only feeling a little rough, I think you will be able to get rid of this algae.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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