Did the vitamin C test, now what?

[Jlsergent]

I have city water but apparently it has iron in it. I have very light stains on my steps and you can see a little staining on the slope of the pool. I did the vitamin C test and it did come off immediately so I assume it is iron. I added some hth metal stain defense and it came off the flat part of the steps but not off the vertical part of the steps.
Being that I have city water and iron is "rare" in city water, could it be something else?
Should I add more of the sequestration stuff or do the ascorbic acid process? Is the ascorbic acid considered a sequester itself? When I read about the process it says to add sequester. Is that something in addition to the ascorbic acid or is the ascorbic acid a sequester itself? I'm just a little confused.
The staining is very light but I would still like it to be gone. Just would like to know the best method so I don't waste a bunch of money on stuff I don't really need.
Thanks!!

 

[JohnT]

The ascorbic acid just removes the stains. It doesn't sequester the metal. You'll probably want to use a sequestrant with phosphonic acid like Jack's Magic products.

The ascorbic acid treatment is incredibly effective and fast.

 

[pooldv]

There is some more info here about managing the sequestrant and water, Pool School - Pool Stains