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Thread: Pool goes yellow when chlorinating or adding shock

  1. Back To Top    #1

    Join Date
    May 2016
    Location
    Montreal,qc
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    5

    Pool goes yellow when chlorinating or adding shock

    Good morning,

    this is is the first year I am opening my pool and i am struggling with an issue.

    ive been able to completly clear the water and get it balanced.. However every time I add shock of chlorine the water tints yellow.
    ive been back and forth to the pool store and all that has been found is very high phosphates( likely from all that leaf organic material over the winter). I've used the phosphate removal product ... But now when I turn on the chlorine generator I get the slight tint of yellow.

    i would like to know can phosphate oxidize and cause this colour when I shock?
    i did ask for a metal test but I am not sure if the pool store ran one or not... Looking for some help and next step in my trouble shooting. I am on city water and have never had any issues... I suspect I should also ask for iron, copper and other metal tests?



    ph 7.4
    ta 140 ppm
    ch 140 ppm


    Thanks
    10000 gal inground
    salt water system

  2. Back To Top    #2
    Richard320's Avatar
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    Jan 2010
    Location
    San Dimas, CA (LA County)
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    18,768

    Re: Pool goes yellow when chlorinating or adding shock

    Sounds like Iron.

    High FC levels react and make it precipitate out of solution and turn to orange rust which looks pale yellow when diluted, and sometimes greenish against the blue background.

    Why are you shocking when you have a SWG? If you get it dialed in to maintain the right FC level at all times, you'll never get algae. I've gone years without ever once shocking my pool, and I don't have an automated system!

    Metal sequestrants will bind with the Iron and make it disappear, although it's still there. Think of a sequestrant as the hard shell on an M&M. The chocolate is there, you just can't see it. When the shell dissolves, then the chocolate starts to melt in your hand.

    If you can get the pool to turn colors for you and layer paper towels in the skimmer, it might trap some of the precipitated Iron so you can just throw it away.



    Also see Pool School - Metals in the Water and Metal Stains
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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  3. Back To Top    #3

    Re: Pool goes yellow when chlorinating or adding shock

    Sounds like it could be from bromide in the water. Has bromine ever been used.

  4. Back To Top    #4

    Join Date
    May 2016
    Location
    Montreal,qc
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    Re: Pool goes yellow when chlorinating or adding shock

    Quote Originally Posted by Richard320 View Post
    Sounds like Iron.

    High FC levels react and make it precipitate out of solution and turn to orange rust which looks pale yellow when diluted, and sometimes greenish against the blue background.

    Why are you shocking when you have a SWG? If you get it dialed in to maintain the right FC level at all times, you'll never get algae. I've gone years without ever once shocking my pool, and I don't have an automated system!

    Metal sequestrants will bind with the Iron and make it disappear, although it's still there. Think of a sequestrant as the hard shell on an M&M. The chocolate is there, you just can't see it. When the shell dissolves, then the chocolate starts to melt in your hand.

    If you can get the pool to turn colors for you and layer paper towels in the skimmer, it might trap some of the precipitated Iron so you can just throw it away.



    Also see Pool School - Metals in the Water and Metal Stains

    Hi hi there is no staining other than pool changing color... I shocked initially as the pool temp was too cold for the swg




    - - - Updated - - -

    Thanks

    I was using shock as the temp was too cold for the swg initially. Yesterday when I dialed it in to generate chlorine I got the same effects.
    10000 gal inground
    salt water system

  5. Back To Top    #5

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    May 2016
    Location
    Montreal,qc
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    Re: Pool goes yellow when chlorinating or adding shock

    Thanks Richard, I meant to post a pic.. see attached pool color.jpg Should I opt for a sequestrant or chelating product? I am going to ask for an Iron test...
    10000 gal inground
    salt water system

  6. Back To Top    #6

    Re: Pool goes yellow when chlorinating or adding shock

    Does the whole pool change color or just where the chlorine is concentrated?

    If it's the whole pool, then it's probably iron. If it's just locally where the chlorine is high and then dissipates, I would think bromide.

    From the picture, it looks like iron.

  7. Back To Top    #7

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    May 2016
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    Montreal,qc
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    Re: Pool goes yellow when chlorinating or adding shock

    Thanks its the whole pool... and intensity is based on chlorine added.. Off to get the metals checked.. thanks!
    10000 gal inground
    salt water system

  8. Back To Top    #8

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    May 2016
    Location
    Montreal,qc
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    Re: Pool goes yellow when chlorinating or adding shock

    So back from the pool store... Seems ph is a little high 8, but all tests for phosphate, iron and copper are clear. I did get a product that should remove other metals going to try it... As they can't identify if there is something else. I'll add the products run for 24 hrs and test again to see if I still get yellow water when chlorinating.
    10000 gal inground
    salt water system

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