Adsorbs ammonia and heavy metals. Highest ammonia adsorption capacity of all zeolites. Removes harmful metal ions such as lead, copper, nickel and zinc. Seachem Zeolite is a highly porous natural mineral that adsorbs ammonia and heavy metals through an ion exchange mechanism. It will not deplete calcium in salt water or increase the overall hardness of fresh water, where ionic strength is low. Seachem Zeolite ™ for units 35, 55, 75 and 110 is pre-packaged in Seachem Zip bags, which feature durable seams and a corrosion-resistant zipper.