Same thing? Let's say similar thing. They are both intermediate strength acids. Res Care smells better. I expect Iron Out to be more effective.
Brine tank is more common and easier. Pulling the valve and dropping either into the media tank would be unusual, but in both, expect the treatment to work inside the media tank. So I think that if you can leave a concentration in contact with the media longer than it would during a regular brine draw regen, then it will be more effective as a one-off treatment.
Adding to the brine tank regularly, and let the treatment just happen during regular regens, works too. There are dispensers to meter Res Care into the brine tank.
Brine tank is more common and easier. Pulling the valve and dropping either into the media tank would be unusual, but in both, expect the treatment to work inside the media tank. So I think that if you can leave a concentration in contact with the media longer than it would during a regular brine draw regen, then it will be more effective as a one-off treatment.
Adding to the brine tank regularly, and let the treatment just happen during regular regens, works too. There are dispensers to meter Res Care into the brine tank.