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Thread: Green pool water??

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    Green pool water??

    We are in year 3 with our pool. The first year we had no problems. We used shock n swim and chlorine tabs, nothing else.

    Last year though it turned brown. It was clear to start with but when I shocked it, it turned brown. We have well water with iron it so I was told to keep the chlorine low and add HTH metal control.

    That cleared it.

    Yesterday we finished filling the pool for this season. The water was clear. Instead of starting with shock and swim I did the Metal out first.

    Now the water is green and you can't see the bottom of the pool.

    What do I do next? ?
    The ph, chlorine and CYA all show low.

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    Mod Squad Patrick_B's Avatar
    Join Date
    Jun 2011

    Re: Green pool water??

    Welcome to the forum.

    Is it clear green or cloudy? Was it clear before you added metal out or had it turned green at all beforehand?
    TFP Moderator
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    Re: Green pool water??

    It was clear. Then I added metal out. It turned green and cloudy. You couldn't even see the bottom.

    My husband decided it needed chlorine. He put shock n swim in it and chlorine tablets in the skimmer.

    Honestly, it looks blue now and only a little cloudiness left.

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    laceygirl's Avatar
    Join Date
    Dec 2013
    Canberra Australia

    Re: Green pool water??

    Hi there

    You need to get yourself a good test kit, so we can diagnose what's in your water...

    Here's the one that TFP recommends...
    Intex Rectangle 18 x 9 x 52', 4544 gallon (18000 litres), 0.75 hp pool pump, 100 sqft Zodiac Titan Cartridge Filter - 40mm, Stenner Peristaltic Pump chlorine injection system, Intex Over The Wall Skimmer, Intex Fittings with 40mm plumbing Lil Patch Of Heaven. Build/Construction

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    BoDarville's Avatar
    Join Date
    Jun 2012
    DFW, Texas

    Re: Green pool water??

    There is a chance that the iron may precipitate out whenever chlorine is added. When you have iron in the water, you need to use sequestrant to bind to the iron and prevent it from redepositing as stains. Unfortunately, sequestrant breaks down over time, you need to be constantly adding more. Sequestrants based on HEDP, phosphonic acid, or phosphonic acid derivatives are the most effective. ProTeam's Metal Magic and Jack's Magic The Pink Stuff (regular), The Blue Stuff (fresh plaster), and The Purple Stuff (salt) are some of the top sequestrants. Also, keep your pH between 7.2 - 7.4.

    One other method you can try, if you can stand the discolored water for a little while, is the "paper towel" method which involves placing about 3-4 sheets of paper towels in the skimmers. The paper towels may remove some of the precipitated metal particles. No guarantee this will work, but it is a low cost - low impact alternative worth trying, so I will put it on the table. Some members have had success with this (see this post: - scroll to post #14 to see a picture of the iron filtered out by the paper towels. If you try this method, check on the paper towels every couple of hours or so while the filter is running. Replace towels as needed.

    Even if the paper towel method removes some of the iron, you will still need to continue using a sequestrant but perhaps less of it if the paper towel method was at least somewhat successful.

    Quote Originally Posted by poolmomma34
    The ph, chlorine and CYA all show low.
    "Low" is rather subjective. It wouldn't hurt to run a complete series of tests on your water to give us a complete picture.
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