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Thread: yellow/mustard algae

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    yellow/mustard algae

    I have been looking all over the internet for the answer to a question. How do I know if yellow/mustard algae is dead? I slammed the pool and kept it at above shock level for 48 hours. I also initially used yellow out. It has been 5 days, appx 40 gallons shock = 80 gallons bleach. My FC level is maintaining/not dropping, the water is pretty much clear until I scrub the bottom/sides of pool. I scrubbed the pool 3x/day throughout the process(I have blisters to prove it). I have a DE filter which I have backwashed and recoated 5-6x. Does it just take time to clear up? Im still getting a "brown dusty film" on bottom and sides of pool- MUCH less every day. Does the algae change to a different color when dead? Im really paranoid the algae will come back as it was alot of work to get to this point. Please help!

    40,000 gallon L shaped pool
    vinyl liner
    36,000 IG
    vinyl liner
    DE filter

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    techguy's Avatar
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    Re: yellow/mustard algae

    Do you know your CYA (conditioner/stabilizer) value from a reagent based test?... Not a computer.

    If your CYA is 100+ ppm, all algae, green, black or mustard, will grow in pools with high FC.
    -- Guy --
    10K gallons in 21' Round 52 inch wall Aqualeader AG, Hayward Power Flow LX 1.5 HP pump motor, Hayward Perflex EC50AC DE filter w/Cellulose, Wide mouth skimmer, 2013 new Diver Dan (craigslist) to replace the faded old Hayward AquaBug. TF-100

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    techguy's Avatar
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    Re: yellow/mustard algae

    Yes, most algae will change color to white or grey but some stay green.
    -- Guy --
    10K gallons in 21' Round 52 inch wall Aqualeader AG, Hayward Power Flow LX 1.5 HP pump motor, Hayward Perflex EC50AC DE filter w/Cellulose, Wide mouth skimmer, 2013 new Diver Dan (craigslist) to replace the faded old Hayward AquaBug. TF-100

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    Re: yellow/mustard algae

    Welcome to the forum.
    I slammed the pool and kept it at above shock level for 48 hours.
    No you didn't SLAM. By it's definition, SLAM removes all the living organics in your pool. You confirm that with an OCLT (Pool School).

    While you certainly elevated your chlorine to SLAM level, you have not completed the SLAM process. Your pool may or may not clear up if you still have algae in your pool

    Performing the OCLT will tell you that the SLAM process is complete.....you really may have stopped too soon.

    Can you post a complete set of test results including CYA.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: yellow/mustard algae

    Unfortunately, I dont have one of those "black dot" CYA tests just the test strips(its on my list). It appears to be 40.
    36,000 IG
    vinyl liner
    DE filter

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    Re: yellow/mustard algae

    Duraleigh, Thats my question.... if I do a OCLT and the FC loss is <1 then I can conclude that the algae is dead?
    36,000 IG
    vinyl liner
    DE filter

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    Re: yellow/mustard algae

    I used the pool school SLAM calculator to SLAM it. The shock FC level at 16.
    36,000 IG
    vinyl liner
    DE filter

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    Re: yellow/mustard algae

    Duraleigh, Thats my question.... if I do a OCLT and the FC loss is <1 then I can conclude that the algae is dead?
    Probably yes but the SLAM process is complete when...
    1. Your pool water is sparkling (your visible debris needs to be cleaned up....it's surely dead algae.
    2. Your CC's are .5ppm or less
    3. You can hold your FC overnight without losing more than 1ppm.

    By far, the most common cause for failure when you SLAM is the rush to stop using so much chlorine....it's human nature and I understand.

    However, you are cleaning up a pool that has been neglected for a good while if you have used that much chlorine to this point.

    Brush, vacuum run your pump 24/7 and do everything you possibly can to get the pool pristine before you allow your chlorine to drift lower than SLAM level.

    The SLAM begins with precise test results and it ends the same way....regardless of the chlorine consumption in between.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: yellow/mustard algae

    Thank you for your input. This clean up has been a nightmare...I want to wake up now!
    36,000 IG
    vinyl liner
    DE filter

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    linen's Avatar
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    Re: yellow/mustard algae

    Welcome to tfp, tracyd

    Quote Originally Posted by tracyd
    Unfortunately, I dont have one of those "black dot" CYA tests just the test strips(its on my list). It appears to be 40.
    Since your cya test is based on test strips, you can almost be certain it's not 40...test strips are not reliable for most measurements and especially not cya. In order to know if you are using a high enough FC level, you need a reliable cya test. Read this pool school article for an appropriate kit: http://www.troublefreepool.com/pool-...kit_comparison

    How do you know you have mustard 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: yellow/mustard algae

    I just called my local pool store to ask if they carry the CYA black dot test in their store and the woman asked "why do you need that?". I told her my whole story/yellow algae. She said I shouldnt use liquid chlorine I should have used Sodium Dichlor stabilized powered shock. I went into the whole raising my CYA level and chlorine lock/ also afraid that powdered chlorine in that much quantity would damage my liner. She said it was nonsense, she has been doing this for 22 years. Am I reading into the whole CYA level/Cl relationshipn too much?
    36,000 IG
    vinyl liner
    DE filter

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    Re: yellow/mustard algae

    She is completely wrong and doesn't know what she is talking about. Yeah, 22 years of making profits selling people chemicals they do not need. Selling stabilized chlorine products (Trichlor and Dichlor), having CYA rise in the pools, some such pools getting algae, people buying more "shock" and other products to help clear their pools including clarifiers, flocculants, enzymes, algaecides, phosphate removers, etc. and weekly shocking. The chlorine/CYA relationship was definitively determined nearly 40 years ago in this paper and has been proven to be true in numerous scientific peer-reviewed papers in respected journals as listed in the "Chlorine/CYA Relationship" section of the first post in the thread Certified Pool Operator (CPO) training -- What is not taught and has been proven in tens of thousands of pools on this and other forums.

    The powdered chlorine would not damage your liner any more than any other source of chlorine unless you dumped it in one place and it settled to the bottom before dissolving. Dichlor dissolves quickly which is probably why she didn't think it was a problem. Cal-Hypo would dissolve more slowly, but again, if one adds chlorine slowly over a return flow and lightly brushes the area where one added it, then it gets fully mixed and will not cause any problems with vinyl. This is also the safe thing to do with chlorinating liquid or bleach since it is denser than water until it gets mixed.

    If you have yellow/mustard algae, you'll need to get into the shadier places it likes to hide such as behind light niches and under removable ladders (if any). Read the Pool School article on Mustard Algae.
    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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