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Thread: Mustard/green film on walls = algae?

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    Mustard/green film on walls = algae?

    I am still considering myself a newbie, although with the help of this forum I have been taking care of the pool by myself for the second season. My question:

    Every week -10 days I see a mustard/green film on the pool walls, mainly in the deep end. It brushes off easily (creates a cloud when brushed). I used the "maintenance" dosage of algaecide occasionally and I do not think I saw any difference.

    Is it algae or just dirt? What should I do? The water is pretty balanced, with PH currently at 7.8, as it tends to drift up every couple of weeks.

    Thanks!
    Guy
    ~20k gallon IG plaster pool, Pentair 3/4HP Whisperflo, Pentair FNS Plus 48 DE filter, IntelliClor IC40 Salt Generator, Pentair Legend Platinum Robotic Cleaner

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    duraleigh's Avatar
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    Re: Mustard/green film on walls = algae?

    Can you post test results?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Mustard/green film on walls = algae?

    SWG with Plaster:

    FC 1.5- 2
    pH 7.8
    TA 70
    CH 220
    CYA 30 (I know, this is low)
    Salt is at 2800
    Guy
    ~20k gallon IG plaster pool, Pentair 3/4HP Whisperflo, Pentair FNS Plus 48 DE filter, IntelliClor IC40 Salt Generator, Pentair Legend Platinum Robotic Cleaner

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    Re: Mustard/green film on walls = algae?

    Anything?
    Guy
    ~20k gallon IG plaster pool, Pentair 3/4HP Whisperflo, Pentair FNS Plus 48 DE filter, IntelliClor IC40 Salt Generator, Pentair Legend Platinum Robotic Cleaner

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    frogabog's Avatar
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    Re: Mustard/green film on walls = algae?

    With a CYA level of 30, the minimum for your SWG is 2ppm.

    Sounds like you're always at or below minimum. My bet is on algae and the need to begin shocking. Do you have a combined chlorine result? (TC-FC=CC).

    Your FC level should be above minimum at all times. That means you need room to lose some chlorine if say... the sun comes out or people swim. I'd shoot for 5-6 ppm.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
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    Richard320's Avatar
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    Re: Mustard/green film on walls = algae?

    [center:26hxefk4]Aha! I see a clue!
    [/center:26hxefk4]
    Quote Originally Posted by guydot
    SWG with Plaster:

    FC 1.5- 2
    pH 7.8
    TA 70
    CH 220
    CYA 30 (I know, this is low)
    Salt is at 2800
    FC 1.5- 2 tells me you're using the color matching test. And even if it's right, it's wrong. With 30 CYA, normal FC is 2-6. You're below that, so you probably are just barely staying ahead of an algae bloom, and every week or 10 days it gets ahead of you.

    You're a prime candidate for the Shock Process. But to do it effectively, you'll need a decent test kit (defined in Pool School) and the How-to directions in
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Mustard/green film on walls = algae?

    Thanks! Sounds like I need to increase the clorine generation from 60 to 80 pervent and add CYA. Is shocking a must in my situation?
    Guy
    ~20k gallon IG plaster pool, Pentair 3/4HP Whisperflo, Pentair FNS Plus 48 DE filter, IntelliClor IC40 Salt Generator, Pentair Legend Platinum Robotic Cleaner

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    Richard320's Avatar
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    Re: Mustard/green film on walls = algae?

    Quote Originally Posted by guydot
    Thanks! Sounds like I need to increase the clorine generation from 60 to 80 pervent and add CYA. Is shocking a must in my situation?
    I'd say so - you have algae.

    Once the process is complete - not before - raise your CYA level up to 70ish, then the SWG can keep up with the losses to sunlight.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Mustard/green film on walls = algae?

    Just to update and contribute to the knowledge base: it was algae. Shocking once then raising CYA and keeping the FC level at about 3ppm did the trick. I have been algae free for weeks now.
    Guy
    ~20k gallon IG plaster pool, Pentair 3/4HP Whisperflo, Pentair FNS Plus 48 DE filter, IntelliClor IC40 Salt Generator, Pentair Legend Platinum Robotic Cleaner

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