Seachem Matrix

Seachem Matrix is a high-capacity biological filtration media that supports the beneficial bacteria which keep your aquarium safe and clear. Each liter provides over 700 square meters of surface area, as much as 170 liters of plastic bio-balls, packed into both the outer surface and a network of internal pores. Those deep pores create low-oxygen zones, so Matrix grows the aerobic bacteria that handle ammonia and nitrite plus the anaerobic bacteria that reduce nitrate, all in the same filter. It is inert, will not break down, and never needs replacing.

Running a Seachem Tidal filter? Grab the pre-portioned Tidal Matrix pouches instead. Otherwise hold this bulk Matrix in a reusable mesh media bag, add Matrix Carbon for chemical filtration, or browse more filter media and cartridges.

What It Does

• Enormous surface area. Over 700 square meters per liter gives beneficial bacteria far more habitat than plastic balls or ceramic rings.
• Full nitrogen cycle. Handles ammonia and nitrite on the surface and reduces nitrate in the deep pores, all in one media.
• Controls nitrate. The oxygen-poor interior lets anaerobic bacteria convert nitrate to nitrogen gas, which most biomedia cannot do.
• Inert and permanent. It does not break down or leach and never needs replacing. Just rinse it when flow slows.
• Freshwater and saltwater. Works in community tanks, planted setups, and reef systems alike.
• Fits any filter. Use it in canisters, sumps, hang-on-back trays, or a media bag in almost any system.

Choose Your Size

Seachem recommends 250 mL of Matrix for every 50 US gallons. Step up for heavier stocking or extra nitrate control.

How to Use

• Place Matrix in your filter after the mechanical and chemical stages so debris is caught before it reaches the media.
• For the best nitrate reduction, keep flow through the Matrix on the gentle side. Slower water lets the anaerobic bacteria work.
• Rinse it in old tank water when flow slows, never in tap water, to preserve the bacteria. It never needs replacing.
• When adding it to an established tank, leave your existing media in place so the biological colony stays stable.

Recommended Pairings

• Seachem Tidal Matrix: the same media pre-bagged to drop into a Seachem Tidal filter
• Weco Mesh Media Bag: a reusable zipper bag to hold bulk Matrix in any filter
• Seachem Matrix Carbon: premium activated carbon for the chemical stage
• Filter Media & Cartridges: browse all media and cartridges

Frequently Asked Questions

How much do I need?

Use about 250 mL for every 50 US gallons. A heavier bioload or a nitrate problem is a good reason to add more.

Does it really lower nitrate?

Yes. The deep pores host anaerobic bacteria that reduce nitrate. Keep the flow through it gentle and give a new setup a few weeks to establish.

Do I ever replace it?

No. Matrix is inert and permanent. Just rinse it in tank water when it clogs and it keeps working for the life of the tank.

Freshwater or saltwater?

Both. Matrix is inert and performs the same in freshwater, planted, and marine tanks.