salt conversion gave brownish stains

Hello and thanks in advance for any help. I just installed an Prologic salt system on a vinyl liner pool I built about 6 years ago. I dumped 400 lbs. of salt in the deep end of an 18,000 gallon pool. When I came back a few hours later to stir up the dissolving salt everything was already turning brown. The steps, skimmers and main drain had a reddish tint to them and the liner had a brownish tint. What can I do to lift these stains, before my clients tell me they want a new liner?

You've almost certainly used salt with a high iron content.

Lowering the pH (near 7.0) and using an HEDP stain remover (Metal Magnet or Pink Stuff) is likely to lift the iron if you move fast.

After that 24/7 filtration and sl-o-w-ly raising the pH will likely deposit the iron on the filter.