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Thread: Question about pucks and stabilizing Chlorine

  1. Back To Top    #1

    Question about pucks and stabilizing Chlorine

    So I have a question/ need some guidance on Chlorine.

    Here's the story:

    The 18th, I opened the pool. I brought Chlorine up to 12PPM (CYA is <30) and held it there until the loss was 1 PPM overnight.
    PH is 7.4, Alk is 90 PPM.
    I went out of town for a week, threw my floater in with pucks. I came back last saturday and it was down to 1 PPM. I shocked it again to 11PPM. It dropped to 4 or 5PPM overnight. I'm confused about why this would be.

    First, shouldn't the pucks have held the level at 3-5PPM?
    Second, can organic material like leaves and pollen cause chlorine to disappate faster? I have trees blooming and I'm wondering it that might be why it won't level off.
    Another thing I'm thinking is that the Phosphates are high and I haven't treated for them with Phos free yet. Could they be causing the chlorine not to stabilize?

    Thanks in advance for the help. Water is crystal clear...just need to get my FC to hold at 3-5 and I'm set!

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: Question about pucks and stabilizing Chlorine

    Welcome to TFP.

    If your FC is dropping overnight you have something consuming it and need to perform a proper shock process until you pass the OCLT.
    Just because you left a floater in the pool doesn't mean it'll keep up with the chlorine demand.
    Organics in the pool will use up FC.

    What test kit do you have?
    Dave J. TFP Moderator
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  3. Back To Top    #3

    Re: Question about pucks and stabilizing Chlorine

    I've got the Chlorine test kit recommended off here with the powder and drops (Pink to clear) last year when getting rid of a mustard problem. Your feedback is what I wanted to hear. I'll hit up costco for more bleach today and give it another go. My larger concern is the 'what' - what organics could it be?

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    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Question about pucks and stabilizing Chlorine

    It's most likely that the chlorine demand was higher than usual because of the low CYA level so more chlorine is lost from the UV in sunlight. The pucks in the floating feeder were probably not enough to keep up so then the chlorine got too low and at some point algae started to grow and that made things even worse since chlorine demand would increase even more. The large overnight drop indicates a high chlorine demand -- probably algae that isn't yet visible (is the water even dull or cloudy if not a full-fledged green algae bloom?). I suspect you've caught this right before it became a full algae bloom. Shock the pool to kill off the nascent algae growth.

    And yes, pollen can also increase chlorine demand. The phosphates don't directly affect demand, but they do provide food for algae growth so when the chlorine level drops too low relative to the CYA level, then the algae can grow faster due to the phosphates. So if you properly maintain the FC/CYA ratio, you don't need to worry about the phosphates because chlorine will kill the algae faster than it can grow. Removing the phosphates is like using an algaecide -- it's insurance if you let the chlorine level get too low, but isn't necessary to do.
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  5. Back To Top    #5

    Re: Question about pucks and stabilizing Chlorine

    Got it thanks. The water this morning was literally crystal clear. No cloud at all could see all the way to the bottom without issue.

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    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Question about pucks and stabilizing Chlorine

    Sounds like you must have caught it just in time. The shock process should go pretty quickly.

    I have some pucks floating in my pool to raise the CYA up a bit. They are dissolving so slowly that I am still having to add bleach every couple days to maintain adequate FC.
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  7. Back To Top    #7

    Re: Question about pucks and stabilizing Chlorine

    So last night I shocked to 11.5PPM and this morning I was at between 10.5PPM and 11PPM; basically no loss.

    So we'll see what happens from here...

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