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Thread: Mustard algae coming back?

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    Mustard algae coming back?

    We recently bought a house with a highly shaded backyard and an onground vinyl pool - 57,000 L. Because I didn't know any better I was using chlorination pucks and was having the local pool store check my water weekly and things started out OK.

    Then I noticed when I turned the pump on in the evening brown stuff was jetting out for the first couple of seconds. I assumed it was just dirt and was backwashing the filter... about 3 weeks ago I realized my pool was not getting enough chlorine with the "add a couple of pucks" strategy my pool store was advocating so I decided to switch to BBB which I'd found by this time.

    At around the same time stains showed up... small clumps of yellowish-green on the liner. I thought it might be mustard algae so I decided I'd shock the pool.

    My levels were

    FC = 0
    TC = 0
    CC = 0.0
    PH = 7.5
    TA = 150
    CH = na
    CYA = 35
    Temp 75ish

    I cranked the FC level up to about 21-22ppm for three days and started brushing regularly. There seemed to be an improvement but the stains were returning a bit each day. So I added 100 ML of polyquat (per the jug) last Wednesday. The pool seemed to improve and the FC was holding steady overnight with no CC. The water looked clearer. There was a noticeable sediment on the bottom of the pool (dead algae?)

    I allowed the FC to come back down and I've now since yesterday been working on lowering the TA with muriatic acid. My current levels:

    FC = 6
    TC = 6
    CC = 0.0
    PH = 7.5
    TA = 120 (this seems odd, I only added 1L of 31.5 % muriatic acid I'm surprised it came down this much?)
    CH = na
    CYA = 35
    Temp 80

    The stains seem to be returning to the pool... did I do something wrong here? Should I reshock? Use more polyquat? I'm not sure how to proceed.

  2. Back To Top    #2
    UnderWaterVanya's Avatar
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    Re: Mustard algae coming back?

    If you really have Mustard Algae - follow this process:

    pool-school/mustard_algae

    The crux of this is that you shock normally then after passing all the criteria really turn the screws on the stuff and go even higher for 24 hours (details in the link) and make sure that all items that go in the pool spend at least an hour in the pool at the high level shock. Lights get pulled out and scrubbed, ladders, etc. Floats go in, pool cleaners, heaters get circulated etc.
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

  3. Back To Top    #3

    Re: Mustard algae coming back?

    I did do that, but went a step further and maintained the mustard algae shock level throughout the entire shock process for extra killing power plus an additional 24 hours after. Everything seemed fine but my FC hasn't even come back down to normal yet, it's not been low enough for me to add more bleach yet, but the algae seems to be returning again.

    I'm wondering if I need to re-supershock or if I should be looking at a higher polyquat dose.. or or or.

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    linen's Avatar
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    Re: Mustard algae coming back?

    Welcome to tfp, icoffey

    How are you getting your test values?

    From your description, I would expect your cya level to be much higher, therefore raising the needed shocking FC level higher.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Mustard algae coming back?

    Identify the stains. organic or metal. Do you know how to test them?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Mustard algae coming back?

    Interesting, I don't know how to test them no.

    I just redid my levels w/ TF100 kit:
    ph 7.2 (and aerating)
    FC 4.5
    CC 0.0
    TC 4.5
    TA 100
    CYA 45 (ish, hard to tell in twilight!)
    CH 230
    Temp 78ish

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    Re: Mustard algae coming back?

    If you can get a tri-chlor tab (ordinary swimming pool "puck") then hold it somewhere directly on the stain for about a minute. If the stain lightens noticeably, it is an organic stain. If it has no effect, it is probably a metal stain.

    Confirm that by crushing up some cheap vitamin C tablets, put them in a sock and then hold the sock directly onto the stain for three minutes or so. If the stain lightens up noticeably it is a metals stain.

    Post back your findings and we'll go from there.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Mustard algae coming back?

    Ok finally got some daylight hours to play with. The test was inconclusive. The "staining" seems to be some sort of very very fine dust in patches on the liner, and whether I put a tri-chlor tab or a sock on it either way it gets disturbed and is brushed away... I left both in place a for a couple minutes to see if it had an effect in the area around the contact zone but nothing either way...

    Not sure what this stuff is?

  9. Back To Top    #9
    linen's Avatar
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    Re: Mustard algae coming back?

    It sounds like either algae or pollen/dirt.

    If you haven't done a OCLT, that is what I would do next (I would probably bring it back up to shock level to do it).
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Butterfly's Avatar
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    Re: Mustard algae coming back?

    Yep, I agree w/linen. Are you brushing the pool?
    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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  11. Back To Top    #11

    Re: Mustard algae coming back?

    Since the staining started I have been brushing, was everyday while shocking but have slowed down since... Under normal circumstances is daily brushing required?

    I'll try the loss test tonight.

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    linen's Avatar
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    Re: Mustard algae coming back?

    If by normal, do you mean when not shocking? While shocking, brushing should be done at least once per day (more is better). During normal operation, brushing is very pool specific. If you have good circulation and maintain your FC level properly, then you may not have to brush as often. Slippery walls/floors are a sign you should be brushing more.

    By the way...I rarely brush my pool
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  13. Back To Top    #13

    Re: Mustard algae coming back?

    I do mean when not shocking. It may be pollen, we have 5 pretty big (80') oak trees in our back yard not sure what they drop out of the sky as we just moved in. It's also very shady obviously.

    Here's a picture of the type of staining I'm talking about, it was taken yesterday and is actually worse today because I didn't brush (was letting it build for the vitamin c test today).



  14. Back To Top    #14
    linen's Avatar
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    Re: Mustard algae coming back?

    If you can brush it, it not metals...so no need to do the vitamin C test. It looks a bit like pollen to me...if you can snag a bit of it, see if it is slimy...if it is, then I would guess algae.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Mustard algae coming back?

    And another pic


  16. Back To Top    #16

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    Re: Mustard algae coming back?

    If it is mostly in shady areas, then it's more likely to be yellow/mustard algae; if in sun and where circulation "settles" then it's more likely to be pollen. If you can carefully collect some and feel it or better yet look under a microscope, then that will be more definitive.
    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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