I haven't seen this addressed and I did search. I have an acid neutralizer. After I installed it I was amazed by how it reduced the red staining in the toilets and fixtures to almost non-existent. It's been a few months now and the staining is back almost to where it was. I see that people add rustout/iron out to water softeners. Is that something that I could do for my AN before a backwash? Is there any reason in particular not to do something like that?

I'm not sure that will fix the issue but I figured it might be worth a shot to add a cup full before a manual backwash every few months.