Hamburger mat filter

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Run-in and planted mat filter in corner version
Schematic representation of a Hamburg mat filter
Corner HMF with sand / gravel barrier before commissioning. Still without a pump.

The Hamburg mat filter is a low-maintenance and purely biological aquarium filter for freshwater aquariums , which supports the microbiological processes that are already taking place through its structure and dimensions. This optimizes the effect of the filter bacteria and reduces the amount of sludge required.

Filter type

The mat filter consists of a transversely mounted to the flow direction foam mat which (is the mat with their narrow sides directly to the rear, bottom and front glass of the aquarium and extends in height above the water level out) due to their installation manner of the water orthogonal with a certain flow velocity is flowed through. Depending on the size of the pool, it is driven by simple air lifters or centrifugal pumps .

The pump is dimensioned by specifying the number of pool circulations per hour (once or twice). In a further calculation step, this results in the mat size, which fixes the flow rate to about 5 - 10 cm / minute. The mat thickness in the direction of flow is about 5 cm. In the case of common standard pools, the mat size is mostly the same as the size of the side window.

The mat is usually placed in the aquarium about 2 cm from the side pane. Heater, thermometer etc. can be used behind the mat. The mat turns gray-brown after a short time and can be populated with Java fern and Java moss . This makes it almost invisible.


There are a few other designs of the Hamburg mat filter. One of the most common variants is the corner version. The mat is bent into a quarter circle and placed in a corner of the aquarium. Either glass or plastic strips are glued to the panes as a stop for the mat, or cable ducts for more stable guidance with thinner mats. A variant for retrofitting that manages with a wide cable duct and a space-saving mat with an integrated pump comes from Jörg Barmwater.

Biological effect

A minimum organic load is required for a mat filter to function. This is given in common aquariums. The Hamburg mat filter cannot replace the water change because it is an aerobic filter and nitrate is the end product. But it ensures an enormous biological stability of the aquarium and oxidizes u. a. NH 4 + and NO 2 - extremely reliable and fast. Due to its active bacteria, it can permanently accumulate heavy metals . A mat filter is not cleaned, at most it is kept practicable. It is sufficient to suck it off superficially every couple of water changes.

The technical and biological aspects of the Hamburg mat filter were first presented to the general public by the aquarist Olaf Deters and its effectiveness was proven.

Equations and approaches

Flow velocity in the filter:

v = flow rate (in cm / min)
Q = pump capacity (in l / h)
A = filter cross-section (in cm²)

This is used to calculate the flow velocity of the mat. The factor 1000 results from the fact that 1 liter = 1000 cm³.

By switching to:

Q = pump capacity (in l / h)
A = filter cross-section (in cm²)
v = flow rate (in cm / min)

the required pump output results depending on the existing filter cross-section and the desired flow velocity.

The dwell time is then calculated from the mat thickness divided by the flow velocity.

The required filter cross-section results

A = filter cross-section (in cm²)
n = pool throughput per hour (in 1 / h)
Q = tank capacity (gross) (in l)
v = desired flow rate (in cm / min)

The following are guidelines:

  • Circulate the contents of the pool once or twice an hour
  • the flow should be 5 to 10 cm / min

Web links

Commons : Hamburger Mattenfilter  - collection of images, videos and audio files

Individual evidence

  1. Jörg Barmwater: Building instructions for space-saving mat for the rear wall for retrofitting ( Memento from August 21, 2006 in the Internet Archive ).