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Thread: after acid cloudy water & won't hold chlorine

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    after acid cloudy water & won't hold chlorine

    Last week the pool plastering company sent a guy by to test removing a large ash stain from my pool. He successfully removed it in a couple of areas with ascorbic acid and some other acid, but a few days later I noticed that the pool water had become cloudy, the ph had dropped below 6.8, and there was no chlorine. I successfully raised the ph to 7.2 with borax, but even after adding 3 gallons of bleach testing showed no chlorine. If anything the pool water is even cloudier.
    Saw in another post that chlorine should be near 0 before using ascorbic acid. Mine was about 3 ppm before the acid tests. Is the acid combining with the chlorine to form the cloudiness? How do I clear up the pool and get the chlorine level back up?
    25K gal gunite pool with Auto Cover and Meyco mesh winter cover. Pump and filter in underground vault below level of returns. New Pebble Fina plaster in 7/2010.

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    Mod Squad Bama Rambler's Avatar
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    Re: after acid cloudy water & won't hold chlorine

    If the FC went to zero during the process, you most likely have an algae outbreak. You need to shock the pool and maintain it until you pass the OCLT.

    Read the pool school article on how to shock properly. Leave the cover open until you're done.
    Dave J. TFP Moderator
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    JasonLion's Avatar
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    Re: after acid cloudy water & won't hold chlorine

    That is normal after that treatment. Ascorbic acid and chlorine destroy each other. You need to keep adding chlorine until you destroy all of the ascorbic acid.

    Cloudy water is also normal after ascorbic acid is used to remove a stain.

    You also need to be careful about raising the FC level too quickly, because that could cause the stain to return. Keep adding chlorine slowly, perhaps 2 ppm at a time, until you can maintain a FC level. Depending on how much ascorbic acid they used that could be a little while.

    It is possible to also get algae while this is all going on. There is no easy way to tell if you have or not at first. But usually you don't.

    Did they tell you to use sequestrant? Most of the things that cause stains that ascorbic acid removes require you to use sequestrant afterwards.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: after acid cloudy water & won't hold chlorine

    They didn't mention a sequestrant or tell us much of anything because they just want to acid wash the whole pool to remove the ash stain left by ashes from a wildfire over the winter. They just did spot tests of ascorbic acid and another unknown acid in a sock or something held next to the stain with our leaf net. Wouldn't have thought that the small amount of acid used would have messed up my pool chemistry so much, but it did. I'll keep adding chlorine.
    If any acid works to remove this stain, maybe I could use CYA in a sock and rub it over the stain? That's some acid I need in the pool anyway.
    25K gal gunite pool with Auto Cover and Meyco mesh winter cover. Pump and filter in underground vault below level of returns. New Pebble Fina plaster in 7/2010.

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    JasonLion's Avatar
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    Re: after acid cloudy water & won't hold chlorine

    Ascorbic acid, muriatic acid, and cyanuric acid are three quite unrelated products. Ascorbic acid is for removing some kinds of stains, muriatic acid for lowering PH, and cyanuric acid for stabilizing chlorine so it won't breakdown as quickly from sunlight. They are not interchangeable.
    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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    Re: after acid cloudy water & won't hold chlorine

    Finally after adding about 5 gallons of bleach to my pool (in 3 quart doses), it started registering about 2 ppm chlorine. Water is still cloudy though. Adding Fiber Clear to my sand filter to see if that works.
    25K gal gunite pool with Auto Cover and Meyco mesh winter cover. Pump and filter in underground vault below level of returns. New Pebble Fina plaster in 7/2010.

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    Re: after acid cloudy water & won't hold chlorine

    Fiber Clear hasn't done anything about the cloudy water. FC at 2.5 ppm. CC at .5 ppm. So I wouldn't think algae would be the problem. Alk at 85, Calcium at 190, and ph at 7.4. Anyone have any ideas?
    25K gal gunite pool with Auto Cover and Meyco mesh winter cover. Pump and filter in underground vault below level of returns. New Pebble Fina plaster in 7/2010.

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