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Thread: Algae Growth pool chemistry seems good

  1. Back To Top    #1

    Join Date
    Apr 2014
    Palm Springs, CA

    Algae Growth pool chemistry seems good

    I have algae growth, starts in hose to pool cleaner, then spreads.

    FAC 3.0
    TAC 3.0
    Salt 3300
    CH 260
    TA 100
    pH 8.0, slightly high as maintenance not done for a few days , generally for most part 7.4 7.6
    Acid 1
    Pho 500

    Pool is heated to 83 degress

    Air temperature 70-85

    Sunlight 9 hours

    Any thoughts?



  2. Back To Top    #2
    Butterfly's Avatar
    Join Date
    May 2007
    South Carolina

    Re: Algae Growth pool chemistry seems good

    Welcome to the forum

    What is the CYA level?

    If you can see algae, you should SLAM the pool. Directions in Pool School. Big white button top right of each page.

    Also need to thoroughly clean the pool cleaner hose, too.

    Post back with any questions. Lots of folks around to help.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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  3. Back To Top    #3
    Charlie_R's Avatar
    Join Date
    May 2013
    Mexico, MO

    Re: Algae Growth pool chemistry seems good

    Question for you, Garthrob--

    Are those numbers from your own testing or from a pool store? What kit do you have?
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

  4. Back To Top    #4

    Join Date
    Jan 2013
    Houston, TX

    Re: Algae Growth pool chemistry seems good

    It's very scientific around here. The cya level is usually the root problem. Don't trust the pool store tests- get one of the recommended test kits.
    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
    Pool School -- Pool Math -- TF-Test Kit

  5. Back To Top    #5
    BoDarville's Avatar
    Join Date
    Jun 2012
    DFW, Texas

    Re: Algae Growth pool chemistry seems good

    Welcome to TFP!

    As others have stated, we need to know the CYA (stabilizer) level in order to conclusively determine if the current chlorine (FC) level for the pool is adequate. Forget the conventional wisdom of maintaining an FC level between 1-3 ppm. The proper FC level is dependent on the pool's CYA level as shown here: Chlorine/CYA Chart.

    I'm assuming from your Salt level test results that you have a SWG pool (suggest adding pool info to signature). Even at the minimum 60 ppm CYA level that we recommend for SWG pools, an FC of 3 ppm is right at the minimum recommended level. If FC were to consistently drop below 3 ppm, that would give algae a foothold to grow. OTOH, is the CYA level is higher than that, then the 3 ppm FC itself is inadequate.

    Since you currently have algae, SLAMming the pool is in order to get rid of it. There again, you still need to know the CYA level in order to dose FC to the proper SLAM level. If the CYA level is greater than 80 ppm, I would do a partial drain & refill to get it in the range of 60-80 ppm. Then you can begin the SLAM. After the SLAM process is completed, I would aim to keep the FC level at the target range shown in the chart for the pool's CYA level.

    Another thought...If this pool is regularly subjected to high bather loads, you would want to dose FC slightly above the target to account for the higher than average chlorine demand that comes with high bather loads.
    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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  6. Back To Top    #6

    Join Date
    Apr 2014
    Palm Springs, CA

    Re: Algae Growth pool chemistry seems good

    Thanks for the help

    I purchased TFT test kit and these are the results

    Total Alkalinity=90
    Calcium Hardness=440
    Phosphates=2500 ppb

    Pool almost clear, algae continues to grow in pool cleaner hose.
    No signs of algae anywhere else.

  7. Back To Top    #7
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Algae Growth pool chemistry seems good

    Your CYA is a little high, but workable with the SWG.

    I would suggest turning off the SWG, raising the FC up to at least 20ppm with bleach, and then Perform the Overnight Chlorine Loss Test.

    Since you are seeing algae and the pool is not clear, I would expect that you will fail and need to follow the SLAM Process which is going to be maintaining a FC level of 35ppm continually until you pass the 3 criteria to stop. Then you can turn the SWG back on and maintain the FC up around 6-7ppm at all times
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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