Out-performs other best grade carbons by at least two-fold! SeaChem MatrixCarbon is a truly unique activated carbon, bead shaped for optimal hydrodynamics. This provides maximum water flow and contact with a high density of adsorptive sites without the compacting common to granular activated carbon. Even when added to distilled water, it does not raise pH above 7.0 MatrixCarbon has the lowest leachable phosphate content of all major carbon brands tested. Marine or freshwater use.