Seachem Purigen Organic Filtration Resin - Fresh and Saltwater 500 ml (116016308)Brand: Seachem Color: white Features: FILTRATION: Purigen ranges in color from almost white (cream) to light yellow. Seachem Purigen is not a mixture of ion exchangers or adsorbents, but a unique macro porous synthetic polymer that removes soluble and insoluble impurities from water SELECTIVITY: Seachem Purigen is an organic filtration resin that works hard to remove nitrogenous compounds and waste produced by fish, corals, and even plants, making