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:
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.