I tried the ascorbic acid treatment and it took a few days (be patient) and did lift some of the stains, but not enough for my liking. So, I'm going to drain and acid wash the pool to see if I can remove more of the stains. My question is when I did the ascorbic treatment I put in Jacks purple magic (I have salt pool) and that kept the metals from falling and staining the plaster for about a month and then stains started to reappear. So, after I do the acid wash should I continue to treat the pool with Jack's purple on a monthly basis? I'ts a little pricey. Any advice would be great!

White plaster pool
Salt
15000 gallons

Trevor