DEIONIZER/DEMINERALIZER/DI SYSTEMS Deionizers, demineralizers and DI systems are different names for the same equipment. Deionization or demineralization is a process to remove ions, minerals and some gases from water. The deionization process removes ions, dissolved solids, gases, and cations and anions including: Sodium, calcium, magnesium, potassium, manganese and iron (cations) Sulfates, bicarbonate, alkalinity, chlorides, nitrates, …