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Thread: When to move from regular shock to mustard algae shock?

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    Join Date
    Aug 2010
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    Maryland
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    When to move from regular shock to mustard algae shock?

    Looking for clarification. Shocking pool for 3 rd time now due to small yellowish green algae spots That disappear initially with regular shock, easily brush away only to reappear a few days later on all but south facing pool walls in pool despite chlorine levels have never lowered below 11 ppm since last shock and no free chlorine loss overnight , 0-<.5 cc and clear water. Filter backwashed regularly. Current levels are:

    Cya 80 ( lowered from 109 by drain and partial refill )
    Ph 7.3.
    Ta 90
    CH 180
    Cl 14.5 but bringing it up to 22 tonight
    Cc 0
    Borates 40
    Salt 2900 (need to add more I know)

    Yesterday Pulled out pool light and scrubbed hidden algae there and will get ladder/ floaties treated as well. Pool was green swamp when we opened 2 months ago butwe thought we got it all but apparently resistant algae is in there still.

    Question is if algae doesn't show up for several days after I brush and there is no fc loss how do I know when to increase chlorine to mustard algae level (44 based on my cya)?
    Pool store tried to get me to use "no staining" copper algaecide but I'm not going down that road!

    Any help appreciated!
    30,000 gal 20x 40 inground vinyl, 3.5 to 8.5 ft deep, intellichlor SWG, pentair 48 sq ft vertical grid DE filter, 1 hp pentair pump+ booster pump for kreepy krawly pool vac, sun ledge, diving board, intellibrite LED pool light, tf100 test kit

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    JasonLion's Avatar
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    Re: When to move from regular shock to mustard algae shock?

    When you pass the OCLT you increase the FC level to mustard algae shock level for 24 hours, and while at mustard algae shock you brush everything, clean pool toys etc. There are complete instructions in Pool School.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Mod Squad woodyp's Avatar
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    Re: When to move from regular shock to mustard algae shock?

    pool-school/mustard_algae
    See if that helps any.
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
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    Join Date
    Aug 2010
    Location
    Maryland
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    Re: When to move from regular shock to mustard algae shock?

    Yes... I have been reading everything I can on pool school and that's how I knew how to pass on the copper algaecide

    I will do ofcla tonight but I suspect it will pass as it has before with clear water and no visible algae) and if I pass it I will nuke he stuff at MA level shock tomorrow and hold 24 hrs. Maybe pool niche was culprit as well. I just hope I'm not damaging my liner by keeping chlorine so high.

    I read after mustard algae shock to lower target chlorine to above normal target levels for a couple of weeks as well. Is this safe for vinyl pool of I use chem geeks chart, adjusting for my CYA?

    I so want to get back to my swg fc target of 5(CYA 80 and lots of sun) but I have to rid this resistant algae first. Tired of seeing it rear it's ugly head and due to a bad back I can't brush pool daily. In fact until this summer never had to at all!!!
    30,000 gal 20x 40 inground vinyl, 3.5 to 8.5 ft deep, intellichlor SWG, pentair 48 sq ft vertical grid DE filter, 1 hp pentair pump+ booster pump for kreepy krawly pool vac, sun ledge, diving board, intellibrite LED pool light, tf100 test kit

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    Re: When to move from regular shock to mustard algae shock?

    Quote Originally Posted by shore1
    I so want to get back to my swg fc target of 5(CYA 80 and lots of sun) but I have to rid this resistant algae first. Tired of seeing it rear it's ugly head and due to a bad back I can't brush pool daily. In fact until this summer never had to at all!!!
    For a CYA of 80, I keep the FC between 6 and 12 ppm. Since you're getting recurring algae, I think that you might benefit from running at these levels for a while.

    If you can maintain very consistent levels, I would suggest keeping the FC at 8 ppm for at least a month.

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