Applied Membranes, Inc. explains that greensand iron filters are specially formulated from a form of glauconite greensand, which is mined as a natural resource. The filters are coated with manganese oxide, which oxidizes manganese, hydrogen sulphide and iron upon contact to prevent rust, according to Water & Wastes Digest.
The grains of manganese greensand are the ideal shape and size to catch and retain small iron, manganese and hydrogen sulphide particles, reports Water & Wastes Digest. The filtering process does not increase the amount of dissolved solids in the treated water supply; this means that there is no need to backwash manganese greensand with every start of a well pump. This process has been used in the United States since the 1950s.
Applied Membranes, Inc. recommends keeping water temperatures cooler than 80 degrees Fahrenheit to allow a greensand filter to work properly. The company notes that these filter beds must be regenerated from time to time, depending on the amount of use; this requires the addition of a weak solution of potassium permanagate powder. Water and Wastes Digest confirms that the only maintenance required for these filters is the addition of dry potassium permanganate powder to the solution tank every one to three months.