This system of recirculating aquaculture has merits of spending minimum seawater and little change in temperature by external factors. Ever, it has problems of waste material accumulation in fish tank and rapid rise in the ammonia level In this study, electrolysis with switching poles were explored to study the characteristic of removal efficiency of ammonia and the phenomenon of polarization by precipitates. The current, which is the most important factor for product of free chlorine, was lower at the same potential in the electrolysis. By reason of decreasing current, yield of free chlorine is declined. Therefore, it should be prevented fouling phenomenon by switching poles.