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Thread: Question about mustard algae SLAM

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    Question about mustard algae SLAM

    I have what appears to be mustard algae in certain places on the pool walls, in the shaded areas. When I brush, it just dissipates, but returns a day or two later. Meanwhile, water looks crystal clear and test numbers are good. I've read the info here about mustard algae, and I understand that first a normal SLAM is needed. My question is, do I need to backwash during a normal SLAM if water is clear and CC is 0? Should I wait to backwash until after I'm at MA shock level, or even wait until after that?

    We're going to be disassembling and cleaning our DE filter later this month before we start using the pool again, so I'm trying to figure out the best time to do the MA shock.
    23,000 gal. IG gunite pool, DE filter, elevated spa with spillover, Polaris 280 cleaner

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    Mod Squad jblizzle's Avatar
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    Re: Question about mustard algae SLAM

    You should backwash when the pressure rises 20-25% over the clean pressure ... nothing to do with what part of the SLAM you are in.
    Jason, TFP Moderator
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    Re: Question about mustard algae SLAM

    I see. So just to clarify, if the pressure isn't 20-25% higher than it is when it's clean, there's no need to backwash? I wasn't sure if backwashing was needed to clear out any lingering MA, and keep it from coming back.
    23,000 gal. IG gunite pool, DE filter, elevated spa with spillover, Polaris 280 cleaner

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    Mod Squad jblizzle's Avatar
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    Re: Question about mustard algae SLAM

    If the FC levels are high enough, the MA should be killed. I suppose it would not hurt anything to clean the filter after you have passed the SLAM and the 24hr MA high FC soak.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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    Re: Question about mustard algae SLAM

    We've had a lot of rain here over the past few weeks, and I was trying to wait for dryer weather to do our SLAM & MA shock to solve the problem first mentioned at the start of this thread. Finally had to start really tackling this MA problem, despite the continued rain forecast. Had DE filter disassembled and cleaned today after noticing a jump in psi and low circulation. The yellow stuff on the walls continued to build in the meantime. I started the regular SLAM today after the filter cleaning, and my numbers are as follows:

    FC 13 (as of sundown - PoolMath says SLAM level is 12)
    CYA 30
    pH 7.2
    CC 0 (has been all along during this MA issue)

    The FC has held well this afternoon since starting the SLAM. I've been sweeping the entire pool, and the water is a bit cloudy as a result. I'm hoping this will clear up as the now-clean filter is able to catch what I stirred up. Pump is running continuously now after being shut off for a couple of days because of excessive psi reading.

    I will check FC in the morning to see how much was lost in the night. If I lost 1 ppm or less, and assuming I'm still showing 0 CC, can I move on into the MA shock with water that's still a little cloudy?
    23,000 gal. IG gunite pool, DE filter, elevated spa with spillover, Polaris 280 cleaner

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    JoeSelf's Avatar
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    Re: Question about mustard algae SLAM

    This might go a little longer because the filter was shut off for a couple of days. SLAM is done when all three criteria are met.
    13700 gal, 32'x16'x54" AG oval, vinyl, Echo Canyon II, 8500 series, Narrow Yard, Safety Fence & Stair, Sta-Rite Crystal Flow T-210WF, 44 GPM, Hayward SP1580TL 1HP Pump, Aqua Luminator, Festiva wedding cake steps, March 2006, TFT-100, Speed-Stir, Sample Sizer. Avatar Credit: TJ Townsend

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    Re: Question about mustard algae SLAM

    I checked yesterday morning, and I passed an OCLT, water is clear again, and still show 0 CCs. I would have moved straight into the MA shock, but it was pouring down rain here yesterday and last night, so my husband wasn't able to get in and remove the lights from their niches. We're supposed to have more rain again today, so we probably can't remove the lights until this weekend when the weather is supposed to clear up. Since I already passed all 3 SLAM criteria, do I need to continue to maintain FC at SLAM level in the meantime until we can start the MA shock?
    23,000 gal. IG gunite pool, DE filter, elevated spa with spillover, Polaris 280 cleaner

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    JoeSelf's Avatar
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    Re: Question about mustard algae SLAM

    Its easier to maintain the FC level than to let it go down & bring it back up if there is anything in the lights.
    13700 gal, 32'x16'x54" AG oval, vinyl, Echo Canyon II, 8500 series, Narrow Yard, Safety Fence & Stair, Sta-Rite Crystal Flow T-210WF, 44 GPM, Hayward SP1580TL 1HP Pump, Aqua Luminator, Festiva wedding cake steps, March 2006, TFT-100, Speed-Stir, Sample Sizer. Avatar Credit: TJ Townsend

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