Seachem Zeolite pouches for the Tidal 35, 55, 75 and 110 Hang On Filters come supplied pre-bagged in Seachem Zip Bags, which feature durable seams and a corrosion-resistant zipper for ease of use. Seachem Zeolite is a naturally occurring, highly-porous mineral that binds ammonia and heavy metals through an ion exchange mechanism. It has the highest ammonia binding capacity of any available zeolite; ten times higher than some products and twice the capacity of the closest competitor. It won't deplete calcium in saltwater, and it won't increase general hardness in freshwater, where the ionic strength is low. Rinse before use. Do not remove Zeolite from its mesh bag. Lay mesh bag lengthways and distribute Zeolite evenly before placing it in the Tidal filter basket above any the foam and below any biological filtration media.