Seachem Sea gel is a blend of matrix carbon and phosguard and is optimized specifically for aquaria where organic color body and acid removal is required without the introduction of phosphate. Matrix carbon 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. Sea gel may also be used in freshwater that is not phosphate-buffered. Comes 100 ml in a stand-up pouch.