Every shrimp breeder has that one tank that practically runs itself — crystal water, baby shrimp grazing everywhere, plants swaying in a barely-there current. More often than you’d think, the secret is a plain sheet of foam standing against the glass. The matten filter aquarium setup turns an entire wall of your tank into living filtration, and it remains one of the gentlest, cheapest ways to filter a planted tank.
How a Hamburg mattenfilter actually works
The design is almost insultingly simple. You stand a sheet of coarse reticulated filter foam across one end of the tank, sealing the edges so water can’t sneak around it. An airlift tube or powerhead behind the foam pumps water out of the rear chamber, and tank water is slowly pulled through the entire foam surface to replace it.
If you’ve read our sponge filter guide for planted tanks, think of the matten filter as the concept taken to its logical extreme — with one clear distinction: a sponge filter is a small foam cartridge on an airstone, while a matten filter is an entire foam wall that becomes a permanent part of the tank.
Because water crosses several square feet of foam at very low velocity, the matten filter is overwhelmingly a biological filter. Bacteria colonize its vast internal surface, converting ammonia to nitrate as water drifts through — while the outer face grows the thick biofilm that shrimplets graze on from birth.
Choosing the right foam: PPI, thickness, and sizing
The foam is the whole filter, so choose deliberately. PPI (pores per inch) sets the coarseness: lower PPI means bigger pores and slower clogging. Two inches (5 cm) of thickness is the standard — enough depth for bacteria without eating half your tank.
| PPI | Best use | Trade-off |
|---|---|---|
| 10 | Fry grow-outs, heavy bioloads | Weak mechanical filtration |
| 20 | Shrimp and planted tanks (the standard pick) | Slight visible particles |
| 30 | Shrimp breeding with extra clarity | Clogs faster |
| 45 | Polishing stages only | Clogs in weeks — not a main filter |
For a planted shrimp tank, 20 PPI at 2 inches thick is the consensus: shrimplet-safe, slow to clog, generous to bacteria. Size the sheet to the tank’s full height and 10–15% of its length — in a classic 10-gallon planted tank setup, that’s roughly 12 inches tall and 3 inches deep. German-made Poret foam (Swiss Tropicals’ Poret foam) is the original standard; any reticulated polyester foam of the same PPI works.
Installing your matten filter, step by step
A DIY build takes about twenty minutes and costs a third of a kit:
- Cut the foam about 0.5 inch taller than the space so it compresses into place and seals the edges. A serrated bread knife cuts foam cleanly.
- Wedge it against the tank end. Friction alone holds in small tanks; larger builds use silicone-sealed glass strips as rails.
- Place the drive behind the foam: an airlift tube with an airstone at its base, or a small powerhead. For 10–20 gallons, a 2–4 watt air pump driving one lift tube is plenty.
- Set the flow. Aim for the water level behind the foam to sit 0.5–1 inch below the main tank — that pressure difference is the engine. More draw just pulls mulm deep into the foam faster.
- Cycle it like any new filter: add an ammonia source and wait 2–4 weeks, or seed with squeeze water from an established filter to halve the time.
Why a matten filter aquarium suits planted and shrimp tanks
Here’s where the design earns its reputation. Water enters a matten filter aquarium across the entire foam face rather than a single intake, so flow is diffuse and slow. That gives low-tech planted tanks three advantages: near-zero surface turbulence (injected CO2 stays dissolved), no intakes that trap shrimplets or uproot stems, and a bacterial bed so large that bioload spikes barely register.
| Matten | Sponge | Canister | Undergravel | |
|---|---|---|---|---|
| Biological capacity | Excellent | Good | Excellent | Good |
| Shrimplet safety | Excellent | Excellent | Needs guards | Good |
| CO2 retention | Excellent | Excellent | Good | Fair |
| Water polishing | Fair | Fair | Excellent | Fair |
| Cleaning frequency | 1–2×/year | Monthly | Every 1–3 months | Rarely |
| Cost | $15–$40 | $10–$20 | $100–$300 | $15–$30 |
The honest trade-off: maximum biology and minimum maintenance in exchange for a visible foam wall and average clarity. In a shrimp breeding tank that’s an easy win. Unlike undergravel filters, which fight rooted plants for substrate space, the foam wall leaves your aquascape untouched. If contest-level clarity matters, pair the matten with a small polishing stage. No-filter setups sit at the opposite end of the effort spectrum — the matten is the middle path with real filtration.
One stocking caution: fish that demand strong current aren’t a natural match for an airlift-driven matten’s gentle flow. If you’re dreaming of a hillstream loach planted tank, drive the wall with a powerhead so you can dial the current up.
Cleaning a matten filter without crashing your cycle
The foam wall is such a huge biological bed that 6–12 months pass before mulm matters. When flow visibly slows, or the level behind the foam drops more than 2 inches below the main tank, it’s time. Clean only during a water change, in siphoned tank water: squeeze the foam gently a few times and put it straight back. Keep it under ten minutes — bacteria start dying within minutes of air exposure. Heavy root feeders like Ozelot sword won’t notice; your nitrogen cycle will thank you for the restraint.
Frequently Asked Questions
What is a matten filter (Hamburg mattenfilter)?
A sheet of coarse filter foam sealed across one end of the aquarium, with an airlift or powerhead behind it drawing water through the foam. German aquarists invented it to give the foam’s huge surface area over to biological filtration. Unlike a sponge filter — a cartridge on an airstone — the matten is a permanent wall.
Is a matten filter good for a shrimp tank?
It’s one of the best shrimp-tank filters available. No intakes trap shrimplets, the diffuse flow won’t stress berried females, and the foam face grows a constant biofilm that babies graze on. Use 20–30 PPI foam at 2 inches thick.
Can I build a DIY Hamburg mattenfilter?
Yes — among the easiest DIY builds in the hobby. You need a sheet of 2-inch reticulated filter foam (20 PPI), an airlift tube or small powerhead, and an air pump. Cut the foam slightly oversized, wedge it in place, and cycle the tank. Cost: $15–$40.
How often should you clean a matten filter?
Once or twice a year. Clean when flow visibly drops or the water behind the foam sits 2+ inches below the main tank. Squeeze gently in old tank water — never tap water, never wring. Over-cleaning kills the bacterial colony.
Will a matten filter strip CO2 from my planted tank?
Barely. CO2 off-gasses when turbulence agitates the surface, and a matten’s flow is diffuse and gentle — far less disruption than a hang-on-back or spray bar. It’s one reason the design suits both CO2-injected and low-tech planted tanks.
The final word: who should run one
If you keep shrimp, breed fish, or run a low-tech planted tank where gentle flow and minimal upkeep matter more than invisible hardware, a matten filter is hard to beat for the money. It asks almost nothing — a yearly squeeze in a bucket — and gives your tank the largest biological filter most hobbyists will ever own. Build the wall, be patient through the cycle, and let it do the work.