Seachem matrix carbon 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 macro porous binding sitesr seachem matrix carbon 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 70 while all carbons contain phosphate regardless of false claims to the contrary matrix carbon has the lowes