The only thing I'm struggling with is gravity flow through the filter. It will work, but it will slow down quickly as it plugs. But, no way to use the well pump to drive through the filter as the iron is not precipitated. Maybe a float controlled sump pump in the "oxidation pond"? A float switch in the pond to control the well pump would work - might need a contactor (relay or motor starter) to turn the pump on and off. All sounds doable.
