Matrix 500mLMatrix 500mL Matrix is a high porosity bio media that provides efficient biofiltration for the removal of nitrogenous waste. Matrix is a porous inorganic solid about 10mm in diameter. Matrix provides both external and internal macrospores surface area. These macrospores are ideally sized for the support of nitrifying and denitrifying bacteria. This allows Matrix to remove nitrate along with ammonia and nitrite, simultaneously.