Mountain Tree Spiral Filter Mat – 3D Bio & Mechanical Media for Koi Pond Filters

The Mountain Tree Spiral Filter Mat is a cut-to-size filter medium for koi pond filter chambers and Bakki showers. Its patented spiral 3D structure catches debris as water passes through and gives beneficial bacteria a place to settle, so one layer contributes to both physical and biological filtration.

The open, water-permeable build lets water and the oxygen it carries move through the mat instead of around it. That matters because the bacteria that process fish waste need a steady supply of both. It suits koi keepers adding a stage to an existing filter, pond builders fitting out custom chambers, and anyone setting up a Bakki shower.

On its own, a filter mat does not make a complete filtration system. It works best as one stage alongside proper mechanical pre-filtration, dedicated biological media, adequate circulation and regular maintenance.

Key Benefits

• Spiral 3D structure: spiral and coarse filaments create an open, three-dimensional matrix that gives bacteria more places to colonise than a flat pad.
• Two jobs in one layer: traps suspended debris while hosting beneficial bacteria, supporting both physical and biological filtration.
• Keeps water moving: the water-permeable structure helps carry oxygen and nutrients to the bacteria living inside the mat.
• Balanced thickness and density: 4 cm thick with moderate density, built to resist rapid clogging while still holding debris.
• Solid hot-melt construction: filaments are fused by hot-melting, giving a firm mat that keeps its shape in use.
• Cut to fit: trim it to the exact footprint of your chamber, tray or Bakki shower level.
• Simple upkeep: rinse with a low-pressure water nozzle, with no scrubbing or chemical cleaners needed.

What Is the Mountain Tree Spiral Filter Mat?

It is a green, 4 cm thick filter mat made by Mountain Tree, a filtration media manufacturer. Spiral filaments and coarse filaments are hot-melted into a single solid sheet. The manufacturer describes it as a multi-functional medium with both physical and biochemical filtration roles.

How the Spiral 3D Structure Supports Filtration

Water entering the mat has to pass through a tangle of spiral and coarse filaments. Larger suspended particles are caught on the way through, which is the physical part of the job. Because the structure is open rather than tightly packed, water keeps flowing even as the mat collects some debris.

How It Supports Beneficial Bacteria

Nitrifying bacteria live on surfaces, not in open water. The spiral filaments create a large, sheltered surface for them to attach to and form a stable colony, supporting step-by-step biological filtration. A new mat needs time to colonise before it contributes meaningful biological capacity.

Why Water Permeability Matters

Beneficial bacteria need a constant flow of oxygenated water and the waste they break down. The mat's moderate thickness and density are designed to let water circulate through it, keeping the colony active. A mat that clogs solid starves its bacteria, which is why permeability matters as much as surface area.

Physical vs Biological Filtration: What to Expect

Physical (mechanical) filtration removes solid waste. Biological filtration converts dissolved ammonia from fish waste into less harmful compounds. This mat contributes to both, but it is not a replacement for a dedicated mechanical stage such as a settlement chamber, brushes, sieve or drum filter. Heavy solid waste reaching the mat will clog it faster and add maintenance, so place it after your main mechanical stage.

Where It Fits in a Koi Pond Filtration System

• Bakki showers and trickle towers, placed above biological media to spread incoming water evenly.
• Multi-chamber filters, as a cut-to-size layer within biological or polishing chambers.
• Custom-built filter chambers where pre-cut media will not fit the footprint.
• Filter trays and boxes that take a flat mat layer.

Who It Is Best Suited For

• Koi keepers building or upgrading a Bakki shower.
• Pond owners adding a biological stage to an existing multi-chamber filter.
• Pond builders and landscape professionals fitting out custom chambers.
• Hobbyists replacing worn or collapsed filter pads with a firmer, cut-to-size mat.

Specifications

Available Sizes

Manufacturer Carton Information (Trade Reference)

These figures describe how Mountain Tree packs bulk cartons for distributors. They are not the retail pack size or a minimum order quantity.

Which Size Should You Choose?

Both sizes are the same material at the same 4 cm thickness, so they filter the same way. The right choice depends only on the shape of the space you are filling.

• 33 × 33 × 4 cm pieces suit smaller Bakki shower levels, filter trays, compact boxes and replacement pads. They often fit with little trimming and are easy to lift out and rinse one at a time.
• 200 × 100 × 4 cm sheets suit large chambers, multi-chamber builds, long troughs and professional projects. Cut to your exact footprint with fewer joins, then into sections you can lift for cleaning.

One 200 × 100 cm sheet covers about the same area as 18 of the 33 × 33 cm pieces.

1. Measure the internal length and width of each chamber, tray or shower level.
2. If the footprint is close to 33 cm square, or a multiple of it, the smaller pieces save cutting.
3. If the footprint is large or irregular, the full sheet gives a cleaner fit with fewer gaps for water to bypass.
4. Plan how you will lift the mat out for cleaning; pieces you can handle easily make maintenance simpler.

Not sure which size fits? Send us your chamber dimensions on WhatsApp and we'll recommend the right format and quantity with the least waste.

Installation and Maintenance

Installing the Mat

1. Measure the internal footprint of the chamber, tray or shower level.
2. Cut to fit with a sharp utility knife or heavy-duty scissors, leaving no gaps at the edges where water could bypass the mat.
3. Position it after mechanical filtration so the heaviest solids are removed before water reaches the mat.
4. Keep it submerged or well covered during use.
5. Shade it from direct sunlight and direct UV light.

Using It in a Bakki Shower

Place the mat above your biological media, such as bacteria house or ceramic/nitrifying rings. Water landing on the mat spreads out evenly before trickling down, rather than channelling through one spot. Keep the shower covered so the mat is not exposed to direct sun.

Cleaning

• Rinse with a low-pressure water nozzle when debris starts to slow the flow through the mat.
• Rinse gently. High-pressure washing strips more of the bacterial colony and is not the manufacturer's recommended method.
• Where practical, rinse in pond water rather than chlorinated tap water to protect the bacteria.
• If you have several mats or layers, clean them on different days so the whole colony is never disturbed at once.
• Do not move or clean the mat when the water temperature is close to 0°C or below.

There is no fixed cleaning schedule. Frequency depends on your fish load, feeding, how well your mechanical stage removes solids, and water conditions. Watch for slowing flow, water pooling on a Bakki shower level, or visible build-up, and clean when you see them.

Frequently Asked Questions

What is the Mountain Tree Spiral Filter Mat used for?

It is a filter medium for koi pond filters and Bakki showers. Its spiral 3D structure traps suspended debris and gives beneficial bacteria a surface to colonise, so it contributes to both physical and biological filtration. It is cut to fit the chamber, tray or shower level it goes into.

Can I use it in a koi pond filter?

Yes. It is designed for pond filtration and can be cut to fit multi-chamber filters, custom chambers and filter trays. Place it after your main mechanical stage so it is not overloaded with heavy solids, and make sure it stays submerged or well covered.

Does it support biological filtration?

Yes. The spiral and coarse filaments provide surfaces where nitrifying bacteria can settle and grow. Like any biological media, a new mat needs time to build a colony before it adds meaningful capacity. How much it contributes depends on your filter design, flow and fish load.

Can it also be used for physical filtration?

Yes, it catches suspended debris as water passes through. However, it is not a substitute for a dedicated mechanical stage such as a settlement chamber, brushes, sieve or drum filter. Sending heavy solids straight onto the mat will clog it faster and increase cleaning.

Which size should I choose for my filter chamber?

Both sizes filter identically. The 33 × 33 cm pieces suit smaller trays and Bakki shower levels; the 200 × 100 cm sheet suits large or irregular chambers where you want fewer joins. Measure your chamber and send us the dimensions if you'd like help choosing.

Can I cut it to fit my filtration system?

Yes. The mat is designed to be cut to different filter sizes. A sharp utility knife or heavy-duty scissors works well. Cut it to fit snugly so water cannot bypass the mat around the edges.

Can I use it in a Bakki shower?

Yes. Place it above your biological media, such as bacteria house or ceramic rings. Water landing on the mat spreads evenly before trickling down through the media below. Keep the shower covered so the mat is protected from direct sunlight.

How should I clean and maintain it?

Rinse it with a low-pressure water nozzle when debris starts to slow the flow. Gentle rinsing, ideally in pond water, removes solids while leaving much of the bacteria in place. Cleaning frequency depends on your fish load and pre-filtration. Do not move or clean it when water is near 0°C or below.

Does the mat need to stay submerged?

Yes. The manufacturer advises keeping it fully submerged or well covered during use, and protected from direct sunlight and UV light. In a Bakki shower, a cover over the shower provides this protection.

Does it replace a complete koi pond filtration system?

No. It is one component. A healthy koi pond still needs mechanical filtration, adequate biological capacity, good circulation, and usually UV clarification, all sized to your pond volume and fish load. If you're planning or upgrading a system, our team can help you design it.

Pairs Well With

• Mountain Tree Spiral Lotus Root Bacteria House II – building a Bakki shower? Lay the spiral mat on top of bacteria house.
• Blue Japanese Filter Mat – compare a denser mat for a different chamber.

Planning or Upgrading Your Filtration?

A filter mat performs best inside a system sized to your pond. Designing a new filter or upgrading one that's struggling? Get your filtration sized around your pond volume and koi, or learn more about our koi pond filtration design service.