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Thread: 30 ppm drop in FC overnight?

  1. Back To Top    #1

    Join Date
    Jul 2011
    Location
    New Orleans, LA
    Posts
    26

    30 ppm drop in FC overnight?

    Back story here if needed:
    http://www.troublefreepool.com/low-s...lp-t35930.html

    Todays test:
    NaCl 3100
    CYA 75
    FC 0.1

    So before I got to read advice from others on waiting to shock my pool (wknd vacation) I added about 1600 ozs of bleach to the pool last night around 9pm in a 2 hour process (cleaning cartridges, skimming, brushing and other things around the yard) in order to bring FC to 30ppm.

    The water is noticably clearer today. It has been cloudy with no direct sun this am. I took water to pool shop at noon and got this 0.1 FC result. How can this be? Seems ridiculous. The guy at the store said there is a 10% chance that the test was "blanked out" by a high reading. So WHAT DO I DO? wait it out or add another 12+ gals of bleach? My test kit is in the mail.

    Salt is now up to 3100 from 2100 yesterday but SWG has not kicked back in. The guy at the shop said "it definitely should be working by now." He also didn't seem to be a fan of liquid chlorine...

    This all might be a little easier if I actually lived on site
    25k gallon rectangular, Cartridge filtered
    New AquaRite T-15 cell and board
    IG Plaster, No idea of pump size/flow rate
    TF-100 kit with the K-1776 salt kit
    Polaris 280
    Still learning, but I've been to pool school!

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
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    Apr 2007
    Location
    SW Indiana
    Posts
    9,089

    Re: 30 ppm drop in FC overnight?

    The pool store probably uses a test that bleached out at a higher level. Dilute your sample with 3 parts distilled water and retest. Multiply the result by 4.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  3. Back To Top    #3
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
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    37,879

    Re: 30 ppm drop in FC overnight?

    Or use the OTO chlorine test, which can very reliably tell you if FC is near zero or not, even if it can't tell you just how high the FC level actually is.
    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

  4. Back To Top    #4

    Join Date
    Jul 2011
    Location
    New Orleans, LA
    Posts
    26

    Re: 30 ppm drop in FC overnight?

    Well, my test kit came in today and my FC really is non-existent (after 13-14 gals). This drives me nuts. Could the bleach be ineffective? Could the pool be to hot (87F)? What would cause it when my CYA is 75-80?

    Now that I'm leaving town for a couple of days should I add anything else to it? for the weekend or try to shock again & with an algal bloom when I get back?

    My instant salinity test on my SWG is up to 2670, but mine and the pool house tests show about 3100, so it's not working efficiently if at all.

    Really at a loss
    25k gallon rectangular, Cartridge filtered
    New AquaRite T-15 cell and board
    IG Plaster, No idea of pump size/flow rate
    TF-100 kit with the K-1776 salt kit
    Polaris 280
    Still learning, but I've been to pool school!

  5. Back To Top    #5
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: 30 ppm drop in FC overnight?

    Too hot has nothing to do with it. That isn't too hot. There is a small chance the bleach had lost it's strength, but that is extremely unlikely unless you bought it at a dollar store.

    Shocking is a process, not something you do once and are done. You haven't finished shocking the pool. You need to bring the FC level back up to somewhere in the high 20s, and keep doing that until you can maintain an FC level overnight.

    If the water was cloudy to start with it is not surprising that it used up that much chlorine. If you leave it alone now, algae will just start growing again and the chlorine you have used up to this point will be wasted.
    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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