Product DescriptionSeaGel 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. The components enhance each other and are ideal for reef and marine use. May also be used in freshwater that is not phosphate buffered.Sizes: 100 mL 250 mL, 500 mL, 1 L, 2 L, 4 L, 20 LWhy It's DifferentAlthough MatrixCarbon has the lowest detectable leachable phosphate content of all major carbon brands tested, some phosphate is still released. Adding PhosGuard to the mix compensates for this. 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.DirectionsUse 500 mL for each 300450 L (80120 gallons*). Use in a filter bag. Rinse in freshwater before use. Use caution, since product will fizz and heat on initial wetting. SeaGel will function 34 months. May also be used in freshwater that is not phosphate buffered.