Iron Stain removal

[Adam welu]

Did the Vitamin C test today and looks like I have some pretty bad Iron staining.
I will use ascorbic acid to lift the stain. Can I then use the polyfill stuffing in the skimmer baskets instead of a sequestering agent?
Why would the poly fill stuffing catch the Iron and my sand filter not?

 

[Texas Splash]

Iron is tricky because of the various stages it can assume. In pool water it is generally in a soluble state, interfering with color changes and causing stains. It's too fine to be trapped by conventional filters. Only when it is extremely aggravated in a precipitating state are we able to see some limited success with filtration, but even then it has to be at a much finer level than sand can provide. Polyfill traps at a finer level and of course is easily disposable if needed. You probably already know that once you do an AA treatment, the iron is still in the water, so unless you exchange that water, you will have to manage the pH and FC carefully while also using a good sequestrant on a recurring basis.