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Thread: More ?s on Vinyl/Stain/Ascorbic Acid: Calling mbar ?

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    More ?s on Vinyl/Stain/Ascorbic Acid: Calling mbar ?

    Mbar, I found your excellent advice re: treating metal stains on vinyl liners with ascorbic acid on poolforum. Thanks! Hoping to do a little follow up here.

    Background: approx 8 year old vinyl IG pool, 22K gals. Have been using metal-based systems (frogger, most recently eclipse-3) with it,
    going to Eclipse about 3-4 years ago. Last year, in particular, a dark stain at the (6') deep end, maybe 20 sq ft. This year, it's bigger and perhaps darker, along with smaller stains in the shallow end. Vitamin-C in a sock lifted the smaller ones, so I followed mbar's advice.

    The large stain got smaller (ie contracted from the edges) and got lighter in spots, so progress. A couple of questions:

    - what's the max amount of ascorbic acid I can use? I already used around 4 lbs to get these results...I am not opposed to spending
    some $ to get this cleaned up, but want to make certain I don't do some damage to the liner by getting the water too acidic. I lowered
    the ph to around 6.5 before doing the ascorbic acid treatment.

    - is it possible that given this developed over years, and has seen shock (which I think helps set the stain) that it is permanent?

    - if more ascorbic and more time (say a day or two) is needed, is it safe for bathers to use the pool?

    I did one treatment, and now have added the sequestering agent and am bringing the ph back up and will be adding the chlorine. Also plan to test to see if what's remaining is organic, rather than metallic. But if there's hope, I will take another run at this in a week or so. Otherwise I will probably deal with this 'til it's time to replace the liner.
    22,000 Gal IG Vinyl
    Sta-rite SD75 DE filter
    Solar Cover

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    mbar's Avatar
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    Hi, when you added the ascorbic acid did you put your filter on recirculate? Sometimes it's good to just let it circulate for a couple of hours until all of the stain is off. You won't damage your liner with the 4 lbs of ascorbic acid - you don't need to take your ph down before using the treatment - the ascorbic acid will do that all on it's own I usually use 1-2 lbs per 10,000 gals. Since your stains have been there a while, I would use a little more ascorbic and pour it right down the side over the stain. Make sure you have the sequestering agent in the water - someitmes the sequestering agent along with low ph will lift a really light stain. So if it were my pool I would add some more ascorbic where the stain is (if you have any left), let it circulate for a couple of hours, then check the ph and bring it back to 7. Check the alkalinity too - because it can get lowered with the treatment. Some sequestering agents also bring your ph down, so it is important to get the ph up as soon as you see all of the stain is gone. You can also put the ascorbic acid in a sock and rub it on the stain itself. The ascorbic acid itself won't damage the liner, but it will bring the ph down and low ph will damage a liner so that is what you want to watch most, So as soon as you see all of the stain is gone, you can put your filter back on filter and bring up your ph to 7 (this is neutral) don't worry if it goes up to 7.2, but not any higher. You can add some polyquat if you are afraid of getting algae. I always start to take my chlorine up the next day, by doing it very slowly. I have gone in my pool the day after using ascorbic acid and as you can see I am fine Really if you get your ph back up and add a little chlorine it is ok to swim in. Let me know if you have any more questions.
    16x33 fiberglass pool sand filter

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    Hi mbar, thanks for the help...

    The first couple of pounds, I had the setting on "filter". After seeing your post on poolforum, I added a couple more with the setting
    on "recirculate." I also put some ascorbic in socks and dropped them onto the stain (pushed it around with the vac pole for a few mins) while on recirculate - for a few hours. Then I added the sequestering agent. While I was rubbing the sock on the stain, it didn't really lift like the newer, lighter stain in the shallow end.

    Now that I know the sequestering agent is in there, I can give it another shot with the ascorbic acid.

    Thanks for the help.
    22,000 Gal IG Vinyl
    Sta-rite SD75 DE filter
    Solar Cover

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    mbar's Avatar
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    Keep your ph at 7 - 7.2 for a couple of days. Is the stain black? I ask this because if it is something growing under the liner, there really is not a way to get rid of it. Sometimes if the water level gets high under a vinyl liner algae can get under the liner, and that is a different problem. Another thing to try, is get a Mr. Clean Magic eraser and rub it on the stains. See if this lifts it off. There is also a product by Jack's Magic that is a stain kit - it has a couple of little tests that tests for different stains - and it may be worth getting it to see what the stain is. Don't worry, we'll get to the bottom of it Keep me informed on how things are going.
    16x33 fiberglass pool sand filter

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    I did think it might be something under the liner, but the ascorbic acid has helped, so I am encouraged. I suppose there could be multiple types of stains, that all seem to blend into the one big one that's there. Will look into these other suggestions and advise, it will take a couple days. Thanks.
    22,000 Gal IG Vinyl
    Sta-rite SD75 DE filter
    Solar Cover

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    So a quick update. Haven't added any more ascorbic, trying to get the ph back up and get some cl in the pool to
    combat algae.

    Interestingly, have had to backwash a lot. Wed night, backwash wasn't working - ie clear water coming out, not muck-laden
    DE. Disassembled filter, cleaned screens...this stuff has the consistency of latex paint and a LOT was not on the screens/grid but in the bottom of the filter. Clean, reassemble, new DE charge....Thursday night, same routine! This time,
    the muck on the screens was orange-ish/pinkish in color (previous night it was white). Copper?

    Now the CL is getting up to around 3 and the pool is clearing nicely (it got very cloudy after the ascorbic on recirculate).

    Today, Saturday, same routine re: the filter, muck is back to white but still the consistency of latex paint. Water is clear, a good deal of (dead, I hope) algae on the bottom. Vac'ed that to waste, will be topping off with well water (tests on it were slightly acidic, low in metals. It goes through some calcium to neutralize it). I think I will be more agressive with backwashing for awhile, not waiting 'til the pressure gets to startup +10psi pressure.

    Once I get the routine back to normal, I will try the stain kit/erasers. BTW, after removing the solar cover today, the stain on the deep end was smaller/lighter, and those in the shallow end almost gone. Progress!
    22,000 Gal IG Vinyl
    Sta-rite SD75 DE filter
    Solar Cover

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