Fouling of membrane is the major scientific lock for electromembrane process intensification limiting their applications. The fouling evolution on ion-exchange membranes was monitored during three consecutive electrodialysis treatments of a solution containing a high magnesium/calcium ratio. Following these experiments, we proposed a mechanism to explain the change in fouling nature on the CEM from a mix of calcite, brucite, and portlandite after the first ED run to a predominant amorphous Mg(OH)(2) after the third run and the formation of calcite cubic crystal on the AEM, although Mg(2+), an inhibitor of CaCO(3) formation, was present in the solution. It was also demonstrated that the nature and structure of the AEM and CEM foulings formed were self-oriented by the formation of the CEM first layer of fouling appearing during the first run. Our findings have implications for electromembrane process fouling control as well as in the understanding of CaCO(3) crystallization phenomena.