This study is to investigate the efficiency for reducing ammonium of natural clay minerals between zeolite and bentonite in different contact time (0, 8, 8, 24, 32, 48, 56 hours), temperature (cold: 0-10 ˚C, room: 23 ˚C, hot: 40-50 ˚C) and dry and saturated with hydrochloric acid absorbents situations. Results showed dry zeolite can absorb ammonium better than bentonite in all of temperature situations and the saturated H+ bentonite can absorb ammonium better than dry bentonite which trend of adsorption was found increasing after 8 hrs. and showed the most adsorption after 24 hrs. at all of temperature. The size of dry zeolite was smaller than dry bentonite and after both absorbent materials saturated with ammonium solution and saturated with hydrochloric solution, it was split to be small size that made more surface area to absorb ammonium.