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Thread: Mustard Algae Problem ??

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    Join Date
    Apr 2015
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    Simsbury, CT
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    Question Mustard Algae Problem ??

    Moved to new home last July. Pool already opened when moved in. No problems until late September until put solar cover on pool. After that, yellowish sand/dust would develop overnight at bottom of pool. I raised chlorine levels, and continued vacuuming, but not successful. Other than the yellowish sand/dust (which I am guessing is mustard algae) on the bottom of the pool, especially in areas where walls meet floor, the water was completely clear and looked clean.

    A pool company opened our pool this year (never again). Water cleared up a few days after opening. Since then I have been unable to keep chlorine in the pool (using combo of trichlor and liquid chlorine) and I have been seeing the yellowish sand/dust on the bottom of the pool again. (no luck with vacuuming, etc- just comes back next day).

    From my reading, I think I need to SLAM the pool. Just want to make sure that is the correct action before I try.

    Readings are at:
    PH - 7.2
    Clorine been running at under 1 (confirmed by pool store) except after adding large amounts of liquid chlorine (it was 4 today after gallon of 12%)
    TA - 100 (pool store analysis said 80)
    CYA - 50 (confirmed by pool store analysis)

    Am I correct that a SLAM is the only way to get rid of the yellowish sand/dust ?
    Should I do further testing before beginning the process ?
    Are these test levels acceptable to begin the SLAM process ?
    Also, I plan to fully clean the DE filter because it was not done last year and I do not know when the last time it was done, should I clean before or after slam?
    Could the solar cover have caused the algae (is there a way to clean?) ?

    Thank you in advance
    In-ground, vinyl, 18 x 36, Hayward DE filter EC65, Haywood pump
    New pool owner, Tf-100 test kit, on well

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    Mod Squad kimkats's Avatar
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    Tallahassee, FL
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    Re: Mustard Algae Problem ??

    I see that you have a TF-100 test kit. Is that what you used to get your numbers?

    If those numbers are from your TF-100 they should be good to go.

    What does your pressure gauge show? I am not as familiar with DE filters. Please do a search to see what needs to be done. I am thinking it might be a good idea to clean it just because it has been so long but am not sure.

    Yes you do need to do a SLAM. There is even a part of the CYA/FC chart that gives levels for a mustard SLAM.

    Good luck and let us know how it goes!

    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

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    Re: Mustard Algae Problem ??

    The first step would be to confirm you have algae. What happens when you brush the "sand/dust"?

    Can you pick any up off the pool floor between your thumb and finger?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  4. Back To Top    #4

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    Re: Mustard Algae Problem ??

    Yes. My numbers are from a TF-100 test kit, so I assume they are good (although, I'm new to this, so they could be off)

    As far as the filter, the pressure is at 10 after bumping and adding new DE, but I can't say this was the "clean" pressure because I'm not sure of the last time the fingers were actually cleaned. (I think on this better to clean and "start fresh" so to speak")

    Also, yes, I can definitely pick it up in my hand, feels like sand / dirt.
    When I brush it just creates a brown dust ball. (that I assume resettles).

    The other thing that does not make sense in terms of it possibly being mustard algae is that there is nothing on the walls (and my pool does not have particularly shady areas).

    Could this just be dirt ?
    Would not opening the main drain have this affect ? (I am still trying to figure out the valves and the pool store opened the pool, but it does not appeal that the main drain is working)


    Thank you again.
    In-ground, vinyl, 18 x 36, Hayward DE filter EC65, Haywood pump
    New pool owner, Tf-100 test kit, on well

  5. Back To Top    #5

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    Re: Mustard Algae Problem ??

    Eureka! If you can pick it up and it feels like dirt/sand, it is not mustard algae.

    So it certainly seems like it is dirt (a pic would help) now to figure out where it is coming from.

    What is the psi on your filter gauge? Is it higher than normal? When did you last backwash/recharge?

    Do you have any reason to believe your filter is spitting this dirt back to the pool? Is their a lot of dirt in the atmosphere?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  6. Back To Top    #6

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    Apr 2015
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    Re: Mustard Algae Problem ??

    I cleaned and recharged the filter yesterday.
    Its running at normal psi.

    Did an overnight chlorine loss test last night and only down .5, from reading that means its not algae?
    (which also makes sense b/c able to pick up in hand and feels like dirt)

    Filter ran today, but didn't seem to get stuff off of floor ? (is it capable of that ?)
    Should the returns (3) (in addition to 2 by stairs that can't be adjusted) be pointing in specific direction to help with better circulation and kick up dirt from the floor?

    Will vacuum tomorrow and see if comes back.
    Should I put sock over return to make sure not spitting back after vacuum?

    (not incredibly dusty / sandy around)
    - can't get clear picture in the rain, will take when clears up
    Last edited by cgakdj21; 06-01-2015 at 07:06 PM. Reason: addition
    In-ground, vinyl, 18 x 36, Hayward DE filter EC65, Haywood pump
    New pool owner, Tf-100 test kit, on well

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