Best metal sequestering agent?

[phillipjko]

There is Magenta stuff, Purple stuff, Pink stuff and blue.. etc. For copper at 0.2 and mostly everything else is fine with salt at 3400. What would be good to maintain the copper. When I opened it on day 1 by day 9 it is clear and crystal. Now it is getting stains again. I cannot drain the pool all the way and maybe just a metal sequestering agent will do. Which one do I need?

[SunnyOptimism]

Metal sequestering agents will not remove metal stains on their own. If they are metal stains (I answered your other post by the way), then you will need to perform an ascorbic acid treatment prior to adding any sequestrant in order to dissolve the metal stains back into the pool water. Metal stains are precipitated metal salts on the liner material, so you first need to redissolve the metal salts and then use a sequestering agent to help keep the metal ions in solution.