Seachem MatrixCarbon 1937 MG TA Classic Cars for sale Treasured Cars. Permitting 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. 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, MatrixCarbon has the lowest detectable leachable phosphate content of all major carbon brands tested. MatrixCarbon outperforms other high grade carbons by at least two fold when compared for total capacity to remove aquarium organic matter, rate of adsorption, and duration of use.