Couple of AA treatment questions

[Steverino]

Over the past couple of seasons, I've noticed a gradual discoloration on our white fiberglass steps (pool is about 14 years old). It is very mild yellow/tan - definitely nowhere near as bad as some of the pics others have posted on here. Last season I tested it with vitamin C and it whitened right up again, so I'm figuring the iron level in the water has been gradually building up (the staining came back again this year). I'm thinking of doing an AA treatment in the next couple of weeks before it is time to close the pool.

Two questions that may be dumb:
1. Will using Jack's Purple by itself have any effect in my mild case without having first done the ascorbic acid treatment? I assume not, but just wanted to confirm.
2. As to what ascorbic acid to use, is this Vitamin C powder appropriate or is not all AA equal? Amazon.com

Thanks in advance!

 

[Texas Splash]

Good morning. I wouldn't expect any sequestrant to lift a stain, only keep it suspended once released from the surface. I have no personal experience with that brand of AA. Should work, but let's see if others can post what AA product they have used. I'll also tag @Donldson just in case I missed anything more specific.

 

[Steverino]

Thanks for the input! Just to be safe I went ahead and ordered the AA from Guardian, one of the suppliers recommended on here. Price looks to be pretty close to the Amazon stuff I linked anyway. I decided I'd better keep the wheels in motion as I usually close the pool in mid-October and I want to have time to get things re-balanced before then, and while the water is still warm enough for the SWG to function.