Will leaving AA in for a few days do any damage?

[markayash]

I still have a few iron stains I want to get out and since my water is 45 degrees and not using any FC this might be a good time.
Would there be any harm in letting it sit for a couple days with the pump off and them balancing PH etc? Then add metal remover and FC.

 

[ajw22]

The AA lifts the iron from the surface. The pump running gets the iron into the water solution. Adding the sequestrant then gives the iron something to bind to to keep it in solution. The pump running with the filter can capture some of the iron. That is the w y the process described in Ascorbic Acid Treatment - Further Reading works.

What you propose is likely to be ineffective and leave stains on the pool surfaces.

 

[superuser]

I had some metal stains when I inherited my pool, and the AA treatment was darned near instantaneous. I sprinkled the AA into the pool around the perimeter with the pump running, and a half hour later went back out and literally brushed clouds of orange off the walls. Almost magic. Followed it up with a sequestrant, then some weeks later did a water change to get CYA down which likely helped to get a good amount out for good. My stains haven't returned. Well, those stains anyway, I still have some other inherited ones to figure out and eliminate.