The POLY-FILTER is non-toxic and harmless to biological filtration because it allows a sufficient amount of ammonia to reach the biological filter in order to sustain the bacteria culture. The POLY-FILTER provides a supplemental means for removal of ammonia when the biological filter is unable to break down the excess ammonia and its concentration increases rapidly. Then the POLY-FILTER adsorbs the excess ammonia while the biological filter readjusts to higher ammonia input levels.