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Thread: Overnight FC Loss

  1. Back To Top    #1

    Join Date
    Sep 2009
    Location
    Galveston, Texas
    Posts
    4

    Overnight FC Loss

    I do not post much, since I usualy search and find answers to many of my questions. But first, I wanted to give thanks to everyone who takes the time to answer and help us new pool owners.

    I am having some staining issues. At this time, I am trying to determine if they are organic or metal. Unfortunately my work schedule and the weather here in Galveston, Texas, has not allowed to me give 100% attention. We are having rain daily, sometimes a light drizzle to the, out of the blue, 10 minute downpour. I plan on taking next week off (not a vacation, but a big honey-do list) and tackling the pool staining issue is a priority. So everyone will get to know me real well then.

    Anyway, my question is regarding the overnight FC loss test. My pump runs from 8 AM to 8 PM. So the pumps are completely off overnight. I have done a couple of preliminary loss tests to get the hang of things and I am showing some loss (1st test 1.5 PPM, 2nd test 2 PPM), but again, both times included an overnight rain (not hard enought to wake you up, but I can tell by the small water pools on the deck). Is it safe to assume the rain could have contributed to the loss? Also, should the pumps be running overnight to keep the chlorine circulating?

    I apologize for the long winded post, but I am actually preparing everyone for the barage that will be coming next week.

    Thanks, Mark
    13,500 IG Pool w/Spa, 50/50 Quartz/Plaster
    Whisper Flo pump, Booster Pump, Triton II Sand Filter, Pentair Model 320 Chlorine In-line Feeder, Ulta-Pure (Turbo Shock/UV ozone generator), Sta-Rite Max-E-Therm gas heater

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Overnight FC Loss

    The pump does not need to be running overnight for the test to be valid. The pump should be running for a little while after you add chemicals and again for a little while before you take a water sample for testing.

    Heavy rains can use up a little chlorine. Light rains don't usually use enough to notice. It isn't the rain so much as debris blown into the pool that uses up chlorine. So, a windy night, even without rain, can use up some chlorine, while a very calm night (no wind) with steady rain won't use up much chlorine.
    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

  3. Back To Top    #3

    Join Date
    Sep 2009
    Location
    Galveston, Texas
    Posts
    4

    Re: Overnight FC Loss

    Thanks for the quick response Jason.

    The time frames for the two tests were as follows (with last results):
    9:30 PM (pump has stopped running for 1 1/2 hours) FC=10, CC=0, TC=10
    6:00 AM (pump still off) FC=8, CC=0, TC=8

    Should I let the pump run until 9:30 (taking my sampe before turning it off)
    Turn pump on 5:00 AM and take sample at 6:00 AM.
    Would this give me more accurate readings?

    Is it common to have a FC loss, but CC=0. I would think if something was consuming the FC, you would have a residiual CC reading.

    Mark
    13,500 IG Pool w/Spa, 50/50 Quartz/Plaster
    Whisper Flo pump, Booster Pump, Triton II Sand Filter, Pentair Model 320 Chlorine In-line Feeder, Ulta-Pure (Turbo Shock/UV ozone generator), Sta-Rite Max-E-Therm gas heater

  4. Back To Top    #4
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Overnight FC Loss

    There isn't any reason to assume there will be CC. You can have algae and never see any CC.

    It would be good to run the pump for about 30 minutes before taking the sample in the morning, but the results are probably fairly close the way you did it.

    An overnight loss of 2.0 means you are close to getting everything, but not quite there.
    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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