I had bad iron stains in my vinyl liner pool last year.
Pool store tested and said there was a "good amount" of iron in the water. I really wish I would have gotten the actual amount from them, but its too late for that...
I did the ascorbic acid treatment per the instructions here. I then used Jacks "magenta stuff" sequestering agent for the rest of the year and always had Fiber Clear (DE alternative stuff) in the sand filter for the rest of the season.
The pool store now claims there is 0 iron in the water, I took it to the only other store in the area that will test for iron and they also said there is no iron in the water. Unfortionatly I have nothing myself that will test for metals.
Is it really possible the iron got filtered out? I didn't think it could.
I haven't done any significant water changes, just the normal backwashing and rain water additions.