I have not treated my 16 year plus old 10,000 gallon plaster pool for iron stains for well over a year now as I have not been well. Now that I am nearly fully recovered I proceeded to do it the other evening.
Followed the standard method with Ascorbic Acid and then draining and refilling, having brought the pool to shock level for 48 hours and letting it settle back to normal levels before doing the AA treatment.
I have used the Jack's Magenta stuff for well over a year the results were ok but not great, stains still re-appeared. I read today in a previous post of Chem Geek's that he felt the Purple stuff was better overall with Iron stains in a well balanced pool which mine normally is. I will now give the Purple stuff a try and hopefully get a longer period of time before I need to redo the AA treatment.
After having put the Ascorbic acid in the pool I added, one bottle of Magenta stuff, in past Iron treatments I primarily used the Purple stuff, and added an entire bottle of Algaecide 60, sometimes in the past I might use 4 oz of Algaecide 60 , it might have been 11 oz, but this time not thinking I poured the entire 32 oz into the pool. I have not been using Algaecide 60 on a regular weekly basis. The entire pool went cloudy as milk. I thought oh no I am going to have to drain and do this again but it was late and I thought I will deal with it in the morning. I realized that there might be an adverse reaction with this much Algaecide 60 and the Magenta or AA stuff or both.
Next morning the cloudiness had gone and the results were spectacular. Even the very faint stains that had normally remained after previous ascorbic acid treatments had gone. The result is that it basically looks like a brand new plaster job, the best I have ever seen. A fortunate mistake indeed.
I re-filled, balanced the chemicals. My wife is amazed as am I. If I have to do this again in a year or two this would be my preferred method.
Previously when the pool was iron treated with the AA method the walls had in areas a very slight greenish/blue streaks on them once drained and a very very faint yellowish tinge to them when refilled which grew darker in time. This time when the pool was drained there were no such stains. There might have been algae growing under the copper stains or vica versa although I am not sure, which may have been protected from the chlorine shock by the iron stains themselves. This is purely a guess.
One other point of interest, prior to draining the pool, after the overnight treatment, I backwashed the filter for the standard 3 minutes but strangely nothing was cloudy as it usually is.
I will now use the Purple Stuff and Algaecide 60 weekly and hopefully will remain relatively stain free.
Really I do not know why it became so clean but what a great dumb mistake.
Anyone have any ideas as to what might have happened?