Seachem Matrix is a high-porosity inorganic biomedia for biological filtration. Seachem describes it as a porous inorganic solid about 10 mm in diameter carrying both external and internal macroporous surface area - over 700 square metres per litre, which Seachem equates to roughly 170 litres of plastic bio-balls. Because it supports both aerobic and anaerobic bacteria, it controls ammonia, nitrite and nitrate together in the same filter.

Seachem's stated dose is 250 mL of Matrix for each 200 L (50 US gallons) of water, so one litre supports about 800 litres. Matrix is completely inert, does not break down, needs no replacing, and can be rinsed without harming the bacterial colony. This page sells the 1, 2 and 4 litre packs; the contents are identical and only the pack size differs.

Please review the listed size, quantity, ingredients and suitability before ordering.