Those items are covered here, Pool School - Pool Stains
I get that they are covered there. My concern is that people will miss the point about draining once they click the post on the AA treatment. I did and I am sure others have as well.
Maybe moving " Generally, there is no practical way to remove iron or copper from the water short of replacing the water with new water that doesn't have any iron or copper in it. You can use a sequestrant to prevent metal stains. Sequestrants bind to the metal and prevent them from depositing as stains. Sequestrants slowly break down in the pool, so you will need to continually add more sequestrant on a regular basis to maintain sufficient level to keep the iron or copper sequestered.
Sequestrants based on HEDP, phosphonic acid, or phosphonic acid derivatives are the most effective. ProTeam's Metal Magic and Jack's Magic The Pink Stuff (regular), The Blue Stuff (fresh plaster), and The Purple Stuff (salt) are some of the top brand sequestrants. There are also other brands with similar active ingredients, some of which are noticeably less expensive."
right after this statement will help.
Inorganic Stains
Many people find out that they have metal in their water when unsightly stains appear. These stains commonly appear shortly after the PH is raised; often when adding chlorine. Fiberglass pools and plastic components are particularly prone to iron and copper stains.