Clearing Iron stains before open?

[BMoreE]

I'm 80% sure I've got iron stains as a "ring" around where the winter water level was (stain happened 2 winters ago, I lived with it all last year as I fought my builder on other possibly related issues.)

Vitamin C held against it under water for a few minutes does seem to lighten it a bit. Now I could do the full AA treatment idea of course.

However, since the stain is completely accessible above the lowered waterline before I open, I was hoping to instead directly treat it somehow. Perhaps with a sponge/brush combo: douse the sponge in AA-saturated water, rub onto the stain, scrub with brush.

Then when I go to open, start with a sequestering agent (Jack's Magic <color?>) as I bring up the pH.

Anyone ever tried this direct-application method, and have recommendations on equipment (sponge-type, or brush type?) and the type of Jack's Magic I should use?

Or - please tell me if i'm stupid and about to create trouble, and I'll just do the full AA after I open before raising pH.

 

[borjis]

Crushed vitamin c tablets in a sock is what I use to spot treat. A handful dissolves within about 4-5 minutes. Use Jack's magic pink stuff sequestrant to keep it gone.

The staining is probably all over and maybe not noticed as much. I'd recommend a full AA treatment.
I was totally blown away at how much more blue my liner was after doing a full AA treatment.

 

[BMoreE]

I actually used a pantyhose to do the spot-test, since it was under water. But right now the stain is above-water, so maybe the sock dipped in water then applied would do the trick? My nature wants to scrub of course...

I'm just hesitant to do the full monty given my other finish problems (I seem to be losing calcium from the walls) that I'd like to not exacerbate.

 

[borjis]

The best way to spot treat, it will need to be underwater I think.