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Thread: AA Treatment

  1. Back To Top    #1

    AA Treatment

    Hi there,

    I`ve a deep 25K gallons inground pool (fiberglass walls with concrete bottom).
    During the winter the alkalinity went up and some metal stained the walls (curiously, only the walls, not the bottom). Plenty of brown spots.
    It is probably copper since 1 year ago I had algae three times and killed it with few quarts of copper based algaecide... Last year in NC there was an invasion of yellow algae. I first checked for black algae but rubbing with chlorine tablets did not change the situation
    Then, I bought some ascorbic acid tablet (2.99$ vitamin C) at the local grocery, and rubbed it on a couple of spots. Amazing.
    The ascorbic tablets work like erasers on pencils drawings!

    Yesterday, I bought 36 lbs of citric acid (it is very cheap, I paid 105$ with shipping), and I will follow the AA instructions. Once the metal is back in solution (if it does not come out, I`ll jump in and rub all the spots with the acid powder and a sock), I plan to drain 2/3 of the pool and refill it. In this way I reduce the CYA (80) and the alkalinity which I kept high to protect chlorine from fluctuating too much under the sun (I probably exaggerated, and that`s the reason the pH went up to 7.8-7.9 and the metal solubility in the water decreased, now the pH is around 7.0 and it will be like that until the end of the citric acid treatment so the metal gets back in solution more easily).

    Regarding draining the pool: some pools can be drained, others can not. It depends on the structure, construction, water table level, position on the yard. My pool can be drained. Four years ago I kept it empty for 1 month while I was patching/sanding fiberglass and painting with epoxy paint. No problems whatsoever. If stains were hard to remove, it would be cheaper for me to drain, rub with ascorbic acid, and respray with a thin coat of epoxy paint.

    I will post updates soon.

    Stefano
    42,000 gallon IG Gunite, Sta-Rite 400H heater, Sta-Rite cartridge filter, mesh cover, integrated Spa, automatic cover.

  2. Back To Top    #2

    Re: Ascorbic Treatment to rid Pool of metal stains

    Quote Originally Posted by buddywiser
    By the way, does anyone know the shelf like of AA? The more you buy, the better the deal. I'm also thinking about trying the Citric Acid as mentioned in the OP's post since it's way cheaper.

    Keep it away from light, in a PLASTIC sealed bag/container, possibly with the anti-humidity bags, in a cold place (not in the attic) and it will outlast your pool.

    Stefano
    42,000 gallon IG Gunite, Sta-Rite 400H heater, Sta-Rite cartridge filter, mesh cover, integrated Spa, automatic cover.

  3. Back To Top    #3

    Re: Ascorbic Treatment to rid Pool of metal stains

    Quote Originally Posted by buddywiser
    This is just the information I was looking for. I ordered some AA from 3 weeks ago and removed my stain. Then I put in some sequestrant. My pH was consistently around 7.2, but 2 days ago, the stains came back out of nowhere. I checked the pH and it was 7.6. So now I guess it's back to the drawing board
    Unfortunately your vinyl liner prevents you to drain easily. Which sequestrant do you use ? How much do you need and how does it work ?
    I usually drain when some mess happens. The city water costs 60-70$ for a refill (no sewer charge once a year) which is much cheaper than all the chemicals to take care of algae....

    stefano
    42,000 gallon IG Gunite, Sta-Rite 400H heater, Sta-Rite cartridge filter, mesh cover, integrated Spa, automatic cover.

  4. Back To Top    #4

    Re: Ascorbic Treatment to rid Pool of metal stains

    Quote Originally Posted by DLSDO
    The goal is to get the precipitated metal off the pool surface and sequestered in solution.
    BTW, solubility of metals in water is higher at high temperature so the stain removal is easier in the summer than in the winter. All metal stains that I know, appeared during the winter while the alkalinity slowly builds up pH and there is not much aereation to take away A.
    42,000 gallon IG Gunite, Sta-Rite 400H heater, Sta-Rite cartridge filter, mesh cover, integrated Spa, automatic cover.

  5. Back To Top    #5
    buddywiser's Avatar
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    Re: Ascorbic Treatment to rid Pool of metal stains

    Quote Originally Posted by auro
    Unfortunately your vinyl liner prevents you to drain easily. Which sequestrant do you use ? How much do you need and how does it work ?
    I usually drain when some mess happens. The city water costs 60-70$ for a refill (no sewer charge once a year) which is much cheaper than all the chemicals to take care of algae....

    stefano
    The pool store near me has BioGuard Pool Magnet Plus, which I read on here is one of the good ones. I added 2 quarts and 2 days later, the stain was gone. That was 2 weeks ago. I'm going to let it go to see how long it takes it to reappear. That should give me a good idea of how often to add a maintenance dose.
    24000 Gal, 18x36 Vinyl
    Hayward Super Pump
    Jacuzzi Tri Clops Cartridge Filter
    Heat Siphon Heat Pump

  6. Back To Top    #6

    Re: Ascorbic Treatment to rid Pool of metal stains

    update on citric acid
    I kept the ph to 7.0 sharp for 1 week and after the 3rd treatment of CA (12 lbs used in total, 4lbs each time) the stains are practically gone, with except 2-3 old ones which will require vitaminC tables hand scrubbing.
    However, the water is cloudy (ph is down) and greenish due to the copper in suspension (cant be algae since I`ve FC=2.5 and the filter is not clogged).
    Tonight I check the pool again and I start draining.
    stefano
    42,000 gallon IG Gunite, Sta-Rite 400H heater, Sta-Rite cartridge filter, mesh cover, integrated Spa, automatic cover.

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