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Thread: Quick question

  1. Back To Top    #1

    Join Date
    May 2011
    Location
    Houston TX
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    20

    Quick question

    Been shocking for a week now and I am still losing a lot of chlorine overnight. Example, last night after the sun went down my FC was 24.5 This morning, it was 12 The pool is crystal clear other than a few spots of black algae that won't die. Will that much clorine be lost to those few spots of black algae?

    cc = .5 as of last night
    cya = 40 as of yesterday
    Ph has been rock solid at 7.4 the whole time.

    Let me know if you need any other numbers.
    16k, DE, IG, Plaster

  2. Back To Top    #2
    benavidescj's Avatar
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    Apr 2010
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    Fleming Island, FL
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    431

    Re: Quick question

    You need to keep that FC level at shock level the whole time. At night the only thing that will make the FC drop is organics. Since you had a large drop at night you need to keep shocking. The reason why it may be taking longer is that you need to MAINTAIN the shock level which in your case is 16ppm. Since in the morning your FC was at 12 it fell below the shock level for your CYA level of 40.
    Carlos
    Pool: 28,000 gallons IG; IC 40 SWG; Pentair 120 gpm cartridge filter; Marble finish; Pentair Wisperflow 1.5 hp; Polaris 360
    Spa: 350 gallon; Bromine
    How to shock your pool

  3. Back To Top    #3

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    Houston TX
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    Re: Quick question

    Ill keep a close eye on it, just seems a lot of chlorine loss for just a few spots of algae. Don't know what else it could be though.
    16k, DE, IG, Plaster

  4. Back To Top    #4
    Mod Squad Bama Rambler's Avatar
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    Re: Quick question

    Are you brushing that black algae with a metal bristled brush? If not you should be.

    Are you testing after dark and before sun up? A few minutes can make a difference.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  5. Back To Top    #5

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    Re: Quick question

    yes and yes
    16k, DE, IG, Plaster

  6. Back To Top    #6

    Join Date
    Apr 2011
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    Somewhere on the Emerald Coast
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    Re: Quick question

    Bama - should a bristled brush be used on plaster?

    Mags - what kind of brush are you using? What is the stiffness of the bristles? How old is the plaster?

    I'm using a fairly soft bristle brush on old plaster that really should be re-plastered. I'm careful to not over-brush the exposed blemishes ... which leads to a nagging question that I have that requires a seperate post - looks like I'll be posting sooner than later. Sorry - didn't intend to hijack this ...
    20,125 gal. (2,690.6 c.f.) In-Ground / Concrete (Gunite) / Pentair Tagelus TA-60-60D Sand Filter / Pentair Whisper Flo Pump Model WF-24 @ 1HP / Hayward Veri-Flo Valve Model 710 / Taylor FAS-DPD K-2006 test kit / Pool School student

  7. Back To Top    #7

    Join Date
    May 2011
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    Houston TX
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    Re: Quick question

    It is a stainless steel 6" brush. If you take it off the pole and use it by hand scrubbing real hard, it will break up the outer layer of crust on the black algae, otherwise the algae laughs at it... The bristles are stiff, but the algae is tougher! The pool was replastered 3 yrs ago and is in great shape. I believe my issue is I left it alone for too long and didn't ever combat the issue. The pool is crystal clear with these spots hanging on. I'm letting the FC level drop down to a non shock level and am going to jump into the pool and tackle it that away. Only real option I have at the moment.
    16k, DE, IG, Plaster

  8. Back To Top    #8
    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: Quick question

    Stainless steel brushes are fine on plaster when the plaster is more than one year old.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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