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Thread: Metal stains and calcium scaling

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    Join Date
    Aug 2008
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    Metal stains and calcium scaling

    JasonLion,

    A fascinating reply, thank you.
    Split off of this topic because this is getting off topic for the original question. JasonLion

    So if I am understanding you correctly to solve the re-staining of iron in pools, which happens to many of us, it would be best to remove the calcium scaling first and then address the the iron issue second, therby denying the iron an easy place to deposit itself.

    If that is so would the best option to solve the re-occuring iron stain issue be to use something like Jack's Magic "The Copper & Scale Stuff" (I know no other), first. Brushing twice daily, or more, with a stainless steel brush as recommended by their tech support, for a week to up to 10 weeks depending on the scaling issue, adding "The Purple Stuff" as needed using their "Sequest Test Kit" to know the amount to supplement. And then use "The Purple Stuff", for a SWG pool, to keep iron in solution once all the scaling has gone.

    The only problem with this solution is that one cannot use the pool until the "The Copper & Scale Stuff" treatment is over. This is achieved by raising the alkalinity to a level of 80 ppm or more with baking soda only from a level of around 20 to 30 ppm. The reasons one cannot use the pool are the pH is held at around 6.5 and the alkalinity at that low ppm.

    They also suggested keeping, if the CYA was 30 ppm, the chlorine at between 1 and 3 ppm. One person told me 1 ppm, and another 3 ppm, 2 ppm of FC is what I came up with using the Chlorine/CyA chart using 67% of the stated minimum FC as it is a salt water pool.

    They did offer another solution that could take many months, even a year, and that was to use "The Purple Stuff" in a SWG pool, keeping the pH at 7.2 and the CH at around 300, and alkalinity at around 80 ppm or lower, effectively doing what you would call a slow in-pool acid wash, until the scaling was removed. The advantage being one could swim in it during that time. But brushing twice daily with a stainless steel brush for up to year is not my idea of pool nirvana. Of course the regular pool cleaner would do some cleaning, or opt out of the daily brushing and just let it take longer.

    Maybe a combination of both methods starting with the "The Copper & Scale Stuff", for say two to three weeks, to give a turbo boost to the process, and then moving on to the "The Purple Stuff".

    Or would a simple old-fashion "Acid Wash" be better, and faster, albeit not very "Green"? For those of us that can drain, or are willing, using this method:

    http://www.poolforum.com/pf2/showthread.php?t=6552

    Do you think any of these suggestions might be a good idea to minimize the re-occuring stain issues from iron? By which I mean get rid of one's scaling first and then concentrate on iron. If you do think it a good idea which treatment method do you think the more ideal?

    Thank for such a clear and concise reply.
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

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    JasonLion's Avatar
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    May 2007
    Location
    Silver Spring, MD
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    Re: Metal stains and calcium scaling

    It all depends on how much calcium scaling you have and how much it bothers you. A full drain and acid wash is the only reliable way to remove calcium scaling, however it also reduces the lifetime of the plaster noticeably.

    To prevent iron stains from coming back, the key is maintaining an appropriate sequestrant level. What level is appropriate in your pool is difficult to predict precisely, since it depends on the metal level, the CH level, the average FC level, etc, and is best determined experimentally.
    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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    Aug 2008
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    Re: Metal stains and calcium scaling

    JasonLion,

    Thank you for your reply.

    I really do not want to shorten the life of my finish so I think I will not do any acid washing.

    "The Purple Stuff" according to Jack's Magic can be used to do an in-pool acid wash, albeit over a long period of time, possibly as long as year. I think I will go with that option although it might use more sequestrant than the normal weekly dose as the the ppm of the sequestrant has to be higher than the maintenance dose. That will make it more costly, but will not be aggresive on the finish.

    Thank you for the time you spent on answering my questions.
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

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