SeaGel, 100 mL Bagged Seagel Is A Blend Of Matrixcarbon And Phosguard Matrixcarbon Is An Ultra Capacity Carbon For The Removal Of Organic And Color Impurities PhosGuard is a powerful remover of phosphate silicate toxic metals and acids Both Components Are Bead Shaped For Optimum Water Flow Characteristics And Penetration The Components Enhance Each Other And Are Ideal For Reef And Marine Use And May Also Be Used In Freshwater That Is Not Phosphate Buffered