Your certified water specialist will need to do some investigating to correctly identify the type of iron present in order to treat it properly. Ferrous (FE++): Ferrous or dissolved iron is the most common. When water containing ferrous iron is drawn from the tap, it appears clear because the iron is still in a dissolved state. Once the water is open to the atmosphere or exposed to oxidation, the iron will begin to precipitate into ferric iron and the water will become golden to orange in color. Ferric (FE++): Ferric iron, also known as ferric hydroxide or oxidized iron, is iron that has already been converted into an insoluble state and will appear as orange sediment. Once iron is converted to this state it can be filtered out using various types of filter media. Bacterial iron: Unlike ferrous or ferric iron that can be diagnosed by the color of the water, bacterial or “live” iron is not readily apparent. It may appear as a feathery or lumpy sediment if visible, and if not properly treated will grow inside the treatment vessels fouling the mineral and causing staining. Colloidal iron: Colloidal iron is comprised of very fine insoluble particles that color the water but will not settle and are almost impossible to filter without flocculation.