Matrix — Biomedia 700 m²/L Nitrification and Denitrification 500 ml, 1 L, 2 L and 4 L - Seachem

Seachem Matrix is a high-porosity biomedia that provides efficient biofiltration for the removal of nitrogenous waste. It is a porous inorganic solid about 10 mm in diameter. Each litre of Matrix provides as much surface area — over 700 m² — as 170 litres of plastic balls. Plastic bio-materials provide only external surface area; Matrix provides both external and internal macroporous surface area. These macropores are ideally sized to support nitrifying and denitrifying bacteria — which allows Matrix, unlike other biomedia, to remove nitrate along with ammonia and nitrite, simultaneously and in the same filter.

Main advantages

• Over 700 m² of surface area per litre — the equivalent of 170 litres of plastic balls
• Internal and external macroporous surface — supports nitrifying AND denitrifying bacteria
• Controls ammonia, nitrite and nitrate simultaneously
• Completely inert — will not break down, never needs replacing
• Rinseable without damaging the filter — most of the bacteria live inside the pores
• Does not affect pH — compatible with all types of wet or wet-dry filters
• Four sizes offered: 500 ml, 1 L, 2 L and 4 L

Directions (Seachem)

Use 250 mL of Matrix for each 200 L (50 US gallons) of water.

Manufacturer's note: this dosage may differ from your packaging. Based on updated studies, Seachem has found that Matrix treats even more water than previously asserted.

• Matrix may be placed in any kind of filter, and is particularly effective in a canister filter
• It is large enough that no filter bag should be required for most applications
• It works well in drip tray systems, though the larger Pond Matrix is better suited to those setups
• Use with Stability to establish the bio-filter more rapidly

Where to place Matrix in the filter

Seachem recommends water flow through filter media in this order:

1. Mechanical filtration (filter floss, sponges)
2. Chemical filtration (MatrixCarbon, PhosGuard, Purigen)
3. Biological filtration (Matrix)

Every filter is different — consult your filter's manual to find its direction of flow.

Maintenance

Matrix does not exhaust over time: you should never need to replace it. It can, however, become clogged with detritus and slime — so regular filter maintenance is recommended. The frequency varies from tank to tank; Seachem suggests once a month as a good starting point for opening and cleaning a canister filter.

Matrix or de*nitrate?

If Matrix is holding your nitrate steady without bringing it down, the manufacturer explains that nothing is broken — it comes down to rate. They compare it to a bathtub: fill it with the spigot wide open and drain it through a straw, and it will overflow. To lower nitrate you need the capacity to remove it at a rate greater than or equal to the rate of formation. Two options: increase the amount of Matrix, or add de*nitrate, which removes nitrate more efficiently per volume of product — provided flow does not exceed 200 L/h (50 GPH). Above that flow rate, stick with Matrix, which supports anaerobic denitrification at higher flow.

If nitrate is already very high (above 20 mg/L), Seachem recommends a water change as the most economical approach before putting these products into service.

Available sizes

• 500 ml
• 1 L — treats up to 800 L (200 US gallons)
• 2 L
• 4 L

Rounding out your filtration

• Seachem Stability — recommended by the manufacturer to establish the bio-filter more rapidly on fresh media
• Seachem de*nitrate — the add-on when nitrate stalls and your flow stays below 200 L/h
• Seachem MatrixCarbon — the chemical stage that comes BEFORE the biological one in the recommended order
• Salifert Nitrate Test Kit — to measure whether removal is keeping up with production

Frequently Asked Questions

Is Matrix just pumice?

Seachem answers this one directly. Both are porous stones, but not every porous stone is the same. Matrix is a specific type, chosen for its extremely high porosity, pore size, durability and inert nature. When you buy Matrix, you are also buying the research that sourced and tested that particular stone, and the assurance that it is safe for aquarium use.

How long before Matrix starts removing nitrate?

It depends on the stage of biological establishment of your tank, the placement of the media and the flow rate. Generally you start to see improvement after a couple of weeks, but every situation varies. Stability speeds up colonization.

Some pieces look darker or lighter than others — is that normal?

Yes. Matrix has natural variations in colour and size, ranging from very light to quite dark. It is normal to see colour differences from one piece to the next.

Can Matrix be rinsed without losing the bacteria?

Yes. Most of the beneficial bacteria live inside the macropores, protected from rinsing. Rinse with aquarium water rather than chlorinated tap water.