Stain Removal Questions

[SuitUp]

Hi! I've been reading this forum for a couple weeks and have learned a lot but still have some questions.

I want to get rid of the stains. Based on info here, I've purchased 2 pounds Vit C, AA powder and EZ Chlor Metal Magnet 32 fluid ozs.

Basically my questions are how do I use these?
1. what does the chlorine level and PH have to be at to do stain removal?
2. which do I do first, Metal Magnet or AA?
3. how long do I run the pump, do I take out the filters because I don't have a circulate only option?

Background: I wanted to remove the stains before swimming season so I started the chlorine removal a few months back. Got a major algae bloom which took a long time to clear and lots and lots of shock because my ph was too high. FINALLY the pool store said to reduce ph, and algae cleared. Now the stains are worse.

Status: Gunnite, 15,000 gals, 4 filter pod, has a heater but I only use it for the attached spa.
ph is now 7.4 and I have not added any chlorine for a few weeks but the chlorine is still holding for some reason. All other levels are in range and have been for the past year, amazingly. Low phosphates and I use Phos Free maintenance. Water clear and we still suit up and swim Chlorine now about 1.5.

Have organic stains in the deep end from debris before we bought the house. These respond to serious scraping with a pumice stone. Lighter stains respond somewhat to a vit c tablet, but they are all over the bottom and sides of the pool. Thanks everyone for this forum!!