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  1. Back To Top    #1


    Hello to All,
    I have spoken to someone about a month ago about the stuff collecting in the bottom of the pool.It appeared brown or black when I first logged on here.My water chemistry was way off at the time,and has since been much more balanced.I have also added a SWG to the system. I have since treated the pool with algaecides,which made it turn grayish/white,then eventually brown/black on the edges.the stuff will keep coming back to the exact same spots in the pool within a day of being brushed.The water is crystal clear.

    Here are the latest test results using a Taylor K-2005:
    FC-3PPM,TC-3PPM,CC-0PPM,PH-7.8--8.0,ALK-110PPM,CYA-70PPM,SALT-4400PPM.The FC level varies some,depending on the type of day.Most are full sun all day with temps in 95/105 range every day.

    I am going to treat this as a Mustard Algae issue and I am ready to nuke the pool with liquid chlorine.My questions are these.

    1) Is my water balanced properly for this ?
    2) How long will I be out of the pool before it is safe to swim again-ballpark figure.

    I am going to use the pool calculator linked to you site for the amount of Chlorine to add.The pool is 18x36x8.5 from which I base a figure of approximately 27k gallons.

    Any insight or help you can give me here will be appreciated.
    18x36 IG vinyle,Sta-Rite System 3 cartridge filter,Pentair IC-40 SWG,Sta-Rite 1 1/4 hp pump,Barracuda G3 pool cleaner,built 2008.

  2. Back To Top    #2
    UnderWaterVanya's Avatar
    Join Date
    Jun 2012
    Mint Hill, NC


    To properly shock you'll need to add the FAS-DPD test to your kit. The Taylor kit you have doesn't have this. That test can be obtained from here.

    I assume you have read this and understand it? pool-school/shocking_your_pool

    And this: pool-school/defeating_algae

    And this: pool-school/chlorine_cya_chart_shock

    And you understand that the target shock value is 28 or higher depending on the process you follow?

    As far as when to swim - in theory anytime the FC is at or below shock value you can swim.
    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
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: Mystery substance.

    The first thing you need to do is run an OCLT to see if it's algae at all. It may just be dirt that's getting deposited in the same places.

    If it's not growing along the shaded sides, it's not mustard algae.

    1. Bring the pH down to 7.2.
    2. Get a FAS-DPD test and run an OCLT.

    It's impossible to say how long it'll take to shock the pool properly. You have to maintain shock level for your cya until you pass the OCLT.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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