"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."
i use this stuff, its alright, i also use phosar in the same bag, maybe i delude myself but mixing them keeps the phosar from sticking together.