Check the listing for details. Seachem SeaGel - Ideal for Planted and Reef Aquaria . Three size options. Condition: New. Listed at 8.49 USD. Seachem SeaGel - Available in three size options **Please note -Only the 100 ML size comes already bagged. The 250 ml and 500 ml DO NOT come bagged.** Seachem SeaGel is a blend of MatrixCarbon and PhosGuard. MatrixCarbon is an ultracapacity 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. Organic & phosphate control The components enhance each other and are ideal for reef and marine use. May also be used in freshwater that is not phosphate buffered. Use 100 ml for each 16-24 gallons. Use 250 ml for each 40-60 gallons. Use 500 ml for each 80-120 gallons. SeaGel will function for 3-4 months Must be used in filter bag for use. Not included with the 250ml and 500ml size