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Thread: Can chlorine cause something in water to turn brown?

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    Can chlorine cause something in water to turn brown?

    Hello all. This is my first post. I first found the site because of a bad algae problem, but after reading up on Pool School, I decided to drain this little pool and start over doing things right this time.

    I am refilling my kids' 12' round Intex vinyl pool (about 2200 gallons, cartridge filter) with water from a spring fed pond. In the pond, water is clear. If I fill a white plastic 55 gallon barrel with the water, it is clear.

    I added bleach and some trichlor as soon as the water started into the pool because it will take about 2 days to fill and I wanted to be sure algae didn't start growing. Pump is not running yet. The pool had just been drained, scrubbed with bleach, then mopped clean. Now, even though water 4 feet deep in the barrel is clear, it is already looking very brown in the pool at only 12" deep. The water is not cloudy, just brown like weak tea.

    I don't think it is anything growing because I tested chlorine and it is off the charts. I expected that because I put in enough to cover the full pool and it's still only about 1/4 full. I have only added Trichlor and a little bleach. I am waiting for it to fill before doing other tests/chemicals.

    What is causing the brown, and what will be needed to get rid of it?

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

    Re: Can chlorine cause something in water to turn brown?

    It's probably iron or some other metal in the water. Liquid bleach has a low pH, which causes the metal to precipitate.

    Use the search box for iron and you'll find lots of threads.
    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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    linen's Avatar
    Join Date
    Jul 2010
    Twin Cities, MN

    Re: Can chlorine cause something in water to turn brown?

    Richard beat me, heres my take...

    Since you describe the water as being clear before chlorinating, and now it is clear but sounds like metals in the water, and it if that is the case, it most likely will not filter out with those intex cartridges. A metal sequestrant may be needed. See:

    You may want take a water sample and have it tested for metals at a pool store or a store that sells water softeners.

    Another possibility, but unlikely since your water was clear to start, is tannins. Tannins and tannin tinting will typically go away with chlorine and time, they may just filter out, though again those intex cartridges filters are not great at doing it. The best way to deal with tannins (it is organic) is to do the shocking process.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  4. Back To Top    #4

    Re: Can chlorine cause something in water to turn brown?

    Thanks guys. I've been working the past week to finish filling the pool and to get the chemical levels where they belong. Even after running the pump for a few days and adding some trichlor shock I've still got the brown tint so it must be the metal as you guys suggested.

    I don't have a local pool store but I do have some chemicals for my hot tub and can buy those at Lowes. I have one called "Stain and Scale" that I believe is the same as the "sequestrants" mentioned in the pool school article but I can't tell you exactly what is in it since I'm not home now. Will that do the trick or can you guys recommend something that can be purchased at Lowes or Walmart so I don't have to drive 30 miles to find a pool store?


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