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Thread: Too much chlorine use after ascorbic acid.

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    Too much chlorine use after ascorbic acid.

    I've had several pools with various problems but this one has me baffled. Bought home in winter 2015. Above ground pool crystal clear when opened. August dark stains appear so I find TFP website and am very impressed. A vitamin C tablet dissolved it in an instant. Late in the season so I decided to wait until opening this year. Cover removed and stains were COMPLETELY gone. I'm confused but curious. August this year they come back. I let the chlorine drop to a safe level and add 3lbs of ascorbic acid and let in run on recirculate overnight and they're gone again. I add a sequestering agent to the skimmer as well. Now there are very faint stains but the pool is using at least three times the chlorine as before. I don't understand why?? The water was complete balanced before I added the three lbs. of acid. Any ideas? If it were metal, why does it disappear under the winter cover?
    HarryO
    24' x 48" dugout to 60'' in center. 15,500 gallon,Haywood sand filter with 3/4 hp doughboy pump

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    Re: Too much chlorine use after ascorbic acid.

    The chlorine is reacting with the ascorbic acid. Until the ascorbic acid is used up, the reaction will continue to consume your free chlorine.
    TreeFiter

    Pool Technician
    Saugerties, NY

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    Re: Too much chlorine use after ascorbic acid.

    Here is the ascorbic treatment:
    Take your chlorine down to 0 and PH down to 7.2, if there is chlorine in the water it won't hurt, it will just eat up the ascorbic acid, so you will need more to get rid of the stains. You can add poyquat 60 per directions on the bottle to avoid getting algae while the chlorine is low.
    You will need about a half to one pound of ascorbic acid per 10,000 gal. I like to go lighter on it and see if all the stains lift off before adding more.

    So were these incorrect instructions? Any idea as to why the stains disappear over the winter? Thank you for your input.
    HarryO
    24' x 48" dugout to 60'' in center. 15,500 gallon,Haywood sand filter with 3/4 hp doughboy pump

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    Swampwoman's Avatar
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    Re: Too much chlorine use after ascorbic acid.

    Nothing wrong with the instructions -- you used 3 lbs on a 15,000 pool, so there was AA left over that FC will fight but ultimately oxidize.

    Your stains may have gone away in winter if your ph lowered...or if you added sequestrant at closing (some people do).
    In ground extended Grecian, 22,000 gal, Hayward 220t sand filter, vinyl liner, dolphin m4 supreme.
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    Re: Too much chlorine use after ascorbic acid.

    Also keep in mind that the instructions are just an approximation, kind of a one size fits all approach. We don't know how much iron there actually is in a stain, therefore we can't calculate exactly how much ascorbic acid will be necessary to completely remove the stain, but leave no extra to eat up chlorine.
    TreeFiter

    Pool Technician
    Saugerties, NY

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