A local dealer recommended a backwashed MTM filter for my low-iron water. Seems to work. It's described as a "manganese greensand equivalent", but is lightweight with good service flow rates, wide effective pH range, and modest backwash requirements. The dealer claims that just backwashing with chlorinated water is sufficient, but most descriptions of the product say it has to be regenerated with potassium permanganate periodically. I'm still trying to get to the bottom of that.