Hello, I recently moved into a rural home with well supplied water after my retrevial pump an iron filter (not under pressure). I'm trying to find out the maintenance schedule for this beast but don't even know what its called. Its a 5000 gallon plastic cistern the water enters the top on call from the retrival pump and water comes out the bottom with little or no iron. Looking into the top of the unit it looks like the iron is building up. Anyone know how to clean this unit or what it is called.