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Thread: Getting rid of Black Algae

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    Getting rid of Black Algae

    My pool is:
    Crystalcrete
    Outdoor / unscreened
    17,000 gallons
    Salt generator
    12 years old
    Hayward C1750 Cartridge filter

    My problem is that for the life of my pool, I would get a few small black spots in etched holes in the concrete starting in late summer. This usually went away by brushing the pool then sprinkling chlorine (originally used some Black Spot crystals then I switched over to just a regular pack of shock) and let it settle to the bottom of the pool overnight (without running the pump). The above process usually took care of things.

    It seems this summer my attack is worse. I am now getting the same stuff in the tile grout around the water line. I have tried the chlorine crystal treatment a few times but it just seems to be alot worse this year.

    Is there any help?

    I did get a little of the black/green stuff from the tile grout and smeared it on white paper. It was interesting because it did not smear too good. Basically crumbled but left a thin dark green smear on the paper.

    (Not that this might make a difference but I was using Jacks Magic for a number of years regulary but quit using it around two years ago)

    Here are my test numbers (from pinch-a-penny testing)
    Total Chlorine = 5.0 ppm
    Free Chlorine = 5.00 ppm
    Combined Chlorine = 0.0 ppm
    pH = 8.0
    Acid Demand = 4
    Total Alkalinity = 160 ppm
    Calcium Hardness = 370 ppm
    Stabilizer = 90 ppm
    Salt = 3,500 ppm

    Thanks for any help.

  2. Back To Top    #2
    Mod Squad kimkats's Avatar
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    Re: Getting rid of Black Algae

    Welcome to the best pool site on the web! We have the way to fix your pool!

    First off you need to do a little learning. I have posted three links for you. One is how to put your pool in your siggy so everyone that reads your posts will know your pool. The second is the meat of what we want you to learn-the ABC of pool water chemistry. The third is a link to show you the BEST water test kits that will help you take control of your pool.

    http://www.troublefreepool.com/conte...efore-you-post

    http://www.troublefreepool.com/conte...ater-chemistry

    http://www.troublefreepool.com/conte...its-comparison

    For right now maybe you can get a cheap ph test to get your ph down. Once you get your ph down you can add a gallon of chlorine/bleach so things do not get worse before you get in a good test kit.

    Once you get a good test kit you will be able to start the SLAM as told in this link:

    http://www.troublefreepool.com/conte...efeating-algae

    I hope you find this helpful and gives you hope that you CAN get rid of the black yuckies forever.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

  3. Back To Top    #3

    Re: Getting rid of Black Algae

    Thanks...
    I ordered a test kit. My ph was at 7.6 just now.

    Can I just use a gallon of store bleach?
    17K gal, IG outdoor uncaged crystalcrete (yr 2002), 1 1/2 HP pump, Hayward 1750C cartridge filter, Hayward SwimPure SWG, No autocleaning --- Southwest Florida

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    Mod Squad kimkats's Avatar
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    Re: Getting rid of Black Algae

    Great! You are on the way!

    Bleach/chlorine-yes you can just use store bleach so long as it is NOT no splash, added smells, etc. It needs to be JUST bleach.

    You should also look around for your best source for bleach/chlorine as far as price and convenience. Here is a neat link to help your figure out the best price.

    http://poncatechsquad.com/Dan/Chlorine/

    Some people find their best price at Walmart, Lowes, ACE Hardware, pool store, etc. Just make sure to check the % AND date code before you buy. With ACE and the pool store you will have to "rent" their jugs but it pays off in the end for me.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

  5. Back To Top    #5
    BoDarville's Avatar
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    Re: Getting rid of Black Algae

    shorembo:

    You might want to check out this article on Black Algae. The key to removing black algae is frequent brushing in order to rupture black algae’s protective barrier so the chlorine can get at it and prevent it from reforming.
    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
    A good test kit is an investment, not an expense.

  6. Back To Top    #6

    Re: Getting rid of Black Algae

    Do I need to adjust my CYA levels prior to slamming the pool? (I know the pH needs to be lowered)

    Here are my test numbers
    Total Chlorine = 5.0 ppm
    Free Chlorine = 5.0 ppm
    Combined Chlorine = 0.0 ppm
    pH = 8.0
    Total Alkalinity = 150 ppm
    Calcium Hardness = 250 ppm
    Stabilizer = 30 ppm
    Salt = 3,500 ppm
    17K gal, IG outdoor uncaged crystalcrete (yr 2002), 1 1/2 HP pump, Hayward 1750C cartridge filter, Hayward SwimPure SWG, No autocleaning --- Southwest Florida

  7. Back To Top    #7
    pwrstrk's Avatar
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    Aug 2012
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    Elverson Pa.
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    Re: Getting rid of Black Algae

    Nope. Your CYA level is fine now for the SLAM process.
    When your done with the SLAM, increase your CYA level to 70-80 for your SWG. You can turn your SWG off for SLAMing. It's your call. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

  8. Back To Top    #8

    Re: Getting rid of Black Algae

    OK, yesterday I put in 2 1/2 gallons of 10% liquid chlorine.

    This morning my chlorine level is now at 25 (CC at 0). Is that OK/Safe?

    My CYA is at 30.
    17K gal, IG outdoor uncaged crystalcrete (yr 2002), 1 1/2 HP pump, Hayward 1750C cartridge filter, Hayward SwimPure SWG, No autocleaning --- Southwest Florida

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