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Thread: fighting with mustard algae - shock level FC but no CC

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    Join Date
    Jul 2015
    Location
    stockbridge/ga
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    4

    fighting with mustard algae - shock level FC but no CC

    Hi everybody. I'm a bit of a noobie here but I seem to have mustard algae, at least when i brush the pool i get clouds of yellowish stuff hitting the water. This just started after a bunch of rain and cloudy days (I'm in Atlanta, GA)
    Before this happened my levels were:
    FC 2.8-3
    CC 0
    TA 75
    CYA 55
    PH 7.6
    Water Temp 89 F

    I ran the SWG at 100% for 36 hours straight and FC went up to 6.5.
    Before I did that I had clear water but yellow stains on the sides (sloping) and floor of the pool. After I ramped up the SWG I had no stains, but when I brushed I had lots of yellow clouds again.

    I lowered my PH to 7.2 and just added 10% bleach to raise FC up to 24 to kill this stuff. What I am confused about is my CC has stayed at 0. Shouldn't this be climbing if the FC was actually killing anything?
    Thanks in advance for any advice.
    27,000 gallon in-ground
    vinyl
    SWG (intellichlor I-40)
    sand filter

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    Texas Splash's Avatar
    Join Date
    Jun 2014
    Location
    South-Central Texas, Marion/San Antonio
    Posts
    12,968

    Re: fighting with mustard algae - shock level FC but no CC

    You can have algae with no CCs. It just means the transformation or oxidation process has not taken effect enough to show-up on your readings. If what you are seeing truly is MA and not just pollen or dust, then your FC levels should be dropping quite a bit each day along with the hot GA sun. Mustard algae is a yellow green color and grows on the walls and floor mostly on the shady side of the pool. Pollen and dirt tends to accumulate in drifts on the floor in places with slower circulation and can often look fairly similar to mustard algae.

    If you determine it really is MA, first you needs to Pool School - SLAM - Shock Level And Maintain, then follow the Pool School - Mustard Algae for 24 hrs. To make sure though, you may want to run an Pool School - Perform the Overnight FC Loss Test (OCLT). And remember, when killing algae during a SLAM, it's not a one-time shock or spike in FC. It MUST be maintained until the 3 SLAM criteria are met.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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  3. Back To Top    #3

    Join Date
    Jul 2015
    Location
    stockbridge/ga
    Posts
    4

    Re: fighting with mustard algae - shock level FC but no CC

    In order to do the OCLT test, or just monitor chlorine loss in general while shocking, should i turn off the SWG and just see what the bleach is doing? Im guessing i can't see the chlorine demand if i am constantly putting in more chlorine
    27,000 gallon in-ground
    vinyl
    SWG (intellichlor I-40)
    sand filter

  4. Back To Top    #4
    Texas Splash's Avatar
    Join Date
    Jun 2014
    Location
    South-Central Texas, Marion/San Antonio
    Posts
    12,968

    Re: fighting with mustard algae - shock level FC but no CC

    You are correct. The SWG must be off or turned to zero at night when doing the OCLT.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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