Seachem 108 Matrix Carbon (2 Liter)MatrixCarbon is a truly unique activated carbon. It is formed as a spherical bead for optimum hydrodynamics, and will not pack. It permits maximum water flow and contact with its high density of macroporous binding sites. MatrixCarbon has a very low ash content as indicated by its minimal impact on pH. Even when added to distilled water, it does not raise pH above 7. 0. While all carbons contain phosphate, regardless of false claims to the contrary,