Feed solution used in the experiments was calcium carbonate solution (CaCO3). In order to avoid any side effect by foreign ions, CaCO3 pure solution, containing only Ca2 +, CO32– and HCO3– ions was used. Because the calcium carbonate solubility in water is very low, it must be added to water saturated with carbon dioxide aiming to form soluble calcium bicarbonate. Therefore, the solution was prepared by dissolving pure reagent grade CaCO3 powder in deionized water under carbon dioxide bubbling: