Matrix 4 L — Biomedia 700 m²/L Nitrification and Denitrification | Seachem

Seachem Matrix 4 L is the largest size in the Matrix range, a high-porosity biomedia designed for efficient biofiltration and nitrogen removal in marine and freshwater aquariums. This 10 mm diameter porous inorganic solid provides a surface area of ​​over 700 m² per liter—the equivalent of 170 liters of plastic balls. Its macropores simultaneously support nitrifying and denitrifying bacteria. The 4 L size treats up to 3200 L (800 US gallons), making it the most economical choice for large reef systems, multiple setups, or aquarists who fill several filters.

Main advantages

• Surface area of ​​over 700 m² per liter — equivalent to 170 liters of plastic pellets
• Internal and external macroporous surface — supports nitrifying AND denitrifying bacteria
• Simultaneously removes ammonia, nitrites AND nitrates in the same filter
• Completely inert — does not degrade, never needs to be replaced
• Rinseable without damaging bacteria — the majority are lodged inside the pores
• 4L size — the most economical in the range, treats up to 3200L (800 US gallons)

Use in reef and marine aquariums

Matrix is ​​unique among biomedia because its macropores support both aerobic bacteria (which remove ammonia and nitrites) and anaerobic bacteria (which reduce nitrates). This dual action allows for complete biofiltration in a single filter. Seachem recommends placing the biological media last in the filtration order: first mechanical filtration (foams, filter floss), then chemical filtration (MatrixCarbon, Purigen, PhosGuard), and finally biological filtration (Matrix). Matrix does not affect the aquarium's pH.

Instructions for use

• 250 ml of Matrix per 200 L (50 US gallons) of water — the 4 L format treats up to 3200 L
• Rinse before use
• Place in a cartridge filter, media reactor, box filter, or any high-flow area of ​​the sump
• Large enough that a filter bag is not required in most applications
• Particularly effective in a canister filter or a dedicated sump compartment
• Use with Seachem Stability to establish the biofilter more quickly

Interview

The Matrix filter does not wear out and never needs replacing. However, it can become clogged with debris and biofilm. Seachem recommends regular filter maintenance—about once a month as a starting point. Since the majority of bacteria are inside the pores, the Matrix can be rinsed with aquarium water to remove debris without damaging the biofilter.

Matrix vs de*nitrate

If Matrix keeps your nitrate levels stable but doesn't lower them, increase the amount of Matrix or add Seachem de*nitrate, which removes nitrates more effectively per unit volume at a flow rate not exceeding 200 L/h. For higher flow rates, Matrix supports anaerobic denitrification more effectively. The necessary anaerobic bacteria typically take a few weeks to colonize the internal pores.

Manufacturer's precautions

• Does not affect pH
• Completely inert — does not degrade
• Compatible with all types of wet or wet-dry filters

Available formats

• 250 ml
• 500 ml
• 1 L
• 2 L
• 4 L

Why choose the Matrix at ReefSolution?

The 4L format offers the best cost per liter in the Matrix range for serious aquarists. It allows you to fill a full canister and a sump compartment simultaneously, or to maintain multiple aquariums. To quickly establish your biofilter, combine Matrix with Seachem Stability. Complete your chemical filtration with Seachem Purigen and Seachem MatrixCarbon.

Frequently Asked Questions

Is the 4L format the most economical in the range?

Yes. The 4L offers the best cost per liter and treats up to 3200 L (800 US gallons). It can fill multiple filters or a large sump and never needs replacing, making it a long-term investment.

Can the Matrix be divided into several filters?

Yes. The 4L bulk format can be divided between a cartridge filter and a sump compartment, or between several aquariums. Dose 250ml per 200L of water per system.

Does the Matrix remove nitrates as effectively as a biopellet reactor?

The Matrix supports anaerobic denitrification thanks to its internal macropores, but functions differently from biopellets, which provide a carbon source for bacteria. For systems with persistently high nitrate levels, combine the Matrix with Seachem de*nitrate or consider a dedicated reactor, depending on the system's organic load.