Hamburger Mattenfilter HMF

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AC Members
Jul 17, 2006
Innsbruck, Austrian Alps

I am new to this forum and would like to know if anybody here is using the Hamburger Mattenfilter HMF ? I was once placing an instruction (an approved tranlation of the original article in the original german language forum) for DIY building and running the cornered version of the HMF somewhere else, but this forum (aquabotanicswetthumb) seems to be offline (why?). If there is a real interest in the topic, i could post it here again, including FAQs and would like to help with that topic(translations, etc.)....



Innsbruck, Austria


AC Members
Jul 17, 2006
Innsbruck, Austrian Alps
I posted the following original article in 2004 at the wetthumbsforum ,which is no longer online. Just thought that it might be useful for some of you.. :) :)
FAqs for the HMF will follow soon.



I'd like to show you a filtration concept that has gaining popularity in Germany and Europe alike but which I couldn't find on any U.S.- pages yet. The principle is that one uses a foam mat and places it against one of the sidewalls of the tank. A standard aquarium pump is placed in the small gap(2 inches)between glass and mat.
Thus the water flows through the mat with a far lower speed but over a higher surface area than in conventionally sized canister filters (in which the current(>>5 inches/sec) usually is too high to establish a bacterial fauna. Olaf Deters published the concept of this rather DIY -like filtration concept on his page and many aquarists "converted" to the HMF ("Hamburger Mattenfilter", to honour the region where it came from) . There is an English-language article explaining the basic principles:
The mattenfilter in English

which tells you more. Here I would like to show you a way of how to implement this idea in a display-aquarium.:

Original author: Jörn Carstens
Translation: Jörg Ortmayr
The original author gave written consent to use his article in this forum.

Construction of a cornered Mattenfilter.

The classical Mattenfilter consists of a foam mat which is jammed in between front and back wall of the tank, parallel to the one of the sidewalls. This principle, which is effective and simple, has been used in many breeding tanks, but has one disadvantage in display aquariums: It doesn't look quite well. One had to look at the front side, often coated with mudparticles, quasi directly into the "sewage plant" of the tank. Clever guys invented the cornered filter, usually placed as a quarter of a circle in one of the corners of the backside. Far away from the frontwalls it is placed far more imposingly.

But a new problem arose: How should one attach the mat ? One couldn't simply jam it between the sidewalls any longer because it tried to regain a straight form due to its elasticity. By this, water always leaked through in between mat and sidewall.

Existing ways for fixings

For stabilization small strips of glas were recommended which were siliconed to the sidewalls of the tank. Disadvantage of this methode: Not every aquarist is familiar with a glascutter und has some rests of glas, even the glazier isn't happy about such mini (?) orders. There always remains the feeling that blurry edges of glas remain. An alternative, plexiglas, available at any home depot, isn’t always easy to handle either. Especially the constant glueing with the panes makes problems, some leakiness always remains. Strips of glas and plexiglas hold the mat only in one direction, so there is only a hold against the pressure of the bent mat itself.
Mechanically better it would be to fix the mat on rails. Sometime, somebody got the idea to use a cablechannel for this.
The cablechannel consists of plastic, is available at any home depot, easily to work with and gives extra fixation to the mat because of its U-like profile.

Cablechannels as holding rails

This idea is discussed here and the simple construction of a cornered Mattenfilter on holding rails made of these cable channels shall be shown on photos. Other technical devices like heater and pump are built in, too.This is shown as an example in a rather small aquarium (50*30*30 cm) . There everything is rather cramped, of course. In all larger tanks the construction is a little bit easier, the special problems of smaller tanks is explained in the text.

Original material

Plastic cable channels are available for little money in the electro department of many home depots, usually in different diameters from 2 metres lenght on. Usually they are used for the installation of cables when they are built in subsequentially, aswell for installations over the plastering or when changes in the cablenetwork have to be done often, as they have a removable cap.
The cablechannels are made of plastics and can be shortened quite easily with an all-purpose saw or a "cutter"-Knife. The cutting shall than be treated with a sharp knife to remove the sharp edge. Afterwards, the channel can be siliconed into the tank.


First on has to determine the size of the mat. You get calculationtools at Olaf's website LINK (see the example section at the end of ths thread) or at JAN RIGHTER's translated site (english ))
The mattenfilter in English

For the construction of a cornered Mattenfilter one needs:

* a mat in the correct size and thickness

* a cablechannel in the necessary dimensions, length = minimum 2x the height of the tank

* silicone

and these tools:

* a yard-stick
* multi-purpose saw (with fine saw-blade)
* a knife to remove the sharp edge (or an awl)
* a pen to write on glas (e.g. Edding)

And these devices for the aquarium

* a pump with power adapted
* heater
* if desired: CO2-system and co..

First steps:

The cable channel as it is sold can be seen on fig.1. In the middle one sees a small piece consisting of the channel in strict sense, and the removed cap (left side). The cap isn't used any more. The mat can be placed in the U-like profile of the channel.
For this project, we use a mat of 3cm (= 1.2 inches) thickness which is placed in a cable channel of 30 x 15 mm dimensions (= 1.2 x 0.6 inches). For thicker mats, larger cable channels have to be used, of course.

Fig. 1: left side: cablechannel as seen in the shop, middle: channel and cup separated, right side: mat in the channel.

After the necessary calculations to find out the sizing of the mat have been done only the radius of the quarter-circle has to be calculated. This radius is the distance from the corner of the aquarium to the middle of the channel. If you forgot how to do these simple calcualations, you will find a tool at Olaf's website.
The channels are then cut to the correct lenght. The lenght should be the distance from the ground of the tank until to one of the bearing sides. Often there is a small protruding gummed hinge of silicone between sidewalls and ground, and also between sidewalls and bearing strip. So it is practical to shorten the cable channel here a little bit or to leave free a small corner. Shortening usually is simpler. It doesn't matter if the channel is shorter here for a few millimetres, this is were the sand or gravel will be later.

Now that the lenght is set one has to mark the distance to the corner of the tank (this distance = the radius of the quartercircle) in order to silicone the channels in the correct position. I use as a correct measure the middle of the cablechannel. One millimetre more or less doesn't matter, the mat is elastically enough to undo smaller errrors. The cablechannels get silicone on their backside and are glued to the position marked before. The result should look like in fig.2. As long as the silicone is still soft smaller corrections can be done, the silicone “sausageâ€should really be consistend (?) so that there is no leak between channel and sidewall and that no small fish might get through.

Fig. 2: The cablechannels are glued, mat is still left.

Those who want can close the contact between cablechannel and sidewall with a seam of silicone, but this is not necessary for its functionability. Now the silicon has to dry, one day should be sufficient. These seams don't have to bear that much load like the walls of the aquarium themselves.

Adding technical devices

Now comes the mounting of the devices. In our example, we want to install a pump and a heater. Especially in smaller tanks there is relatively little place left behind the mat, it is rather narrow. Then it pays to invest some time to find the correct pump or correct heater (speaking of dimensions). For tanks larger than 100 litres (> 25 G) the place behind the mat usually is large enough to fit in any standard size pumps and heaters.

Fig. 3: Mounting of technical accessories

For the heater, there are usually only a few ways to place it. In these small tanks, one should try to position it not below the bearing sides so that the cable can go freely upward and one can adjust temperature, if necessary. So the small pump had to be placed below the bearing side. In this example the pump was mounted rather high above. When doing a water change, it will run dry (which can be accepted for a few minutes) or has to be stopped. On the other side, it can easily distribute the warm and rising water from the heater. If one installed the pump more below, as it is assigned sometimes, one would have to build a tube from the pump-outlet upwards, including two 90°-bends. There is no place for that here and it needs additional material.
Here a small garden hose is set upon the pump (it doesn't have to be a yellow rest of a garden hose like in the picture)

Fig. 4: Mount the hose on the pump outlet.

It is recommended to use a hose that is bent a little bit, so that the tank is flown through diagonally. That way one gets the best temperature dispersion. The hose should also be bent a little bit upward, so that one gets a small movement of the water surface. . One has to find out during operations wich is the best position. Now you make a crosslike cut into the mat where the hose is passed through. Then, or rather simultaneously, the mat is pressed into the two cable channels.
This looks like in Fig. 5.

Fig. 5: et voilà : the mat in front, Finished !

In these small setups one needs a little bit of skill and patience due to their narrowness, in larger tanks (and therefore larger cornered Mattenfilters) it is easier. If the dimensioning of the mat allows, a place of about 10 cm (= 3.9 inches) should remain, then one can still work rather easily behind the mat. .A view from above shows how little place is left in this "mini" tank.

Fig.6: Little place in a "mini" tank

In the space behind the mat one can mount the thermometer or the (yeast methode) CO2-outlet below the pump. In larger tanks one usually has more comfort. But one sees how simple a construction for a cornered Mattenfilter can be. As well from the materials needed as for the time. . It is recommended to fill the tank with water and let the pump work for trial. That way smaller incontaminations (like from solvents) are washed out and one can trim the devices, if necessary.

Masking of the filter.

At first sight, now one has a round box in a high intensity blue (depending on mat colour). Not everybody's favourite. But: one sees no longer the suction tube of the filter, heater, etc… in the tank because everything is hidden behind the mat.
But, no fear (?), this view will change. The bacteria which settle will turn the colour of the mat to a dark blueblack to brownblack- In the next figure one sees a 5 week old Mattenfilter in a 80 litres ( 21 USG) standard-size-tank without fish but with snails.

Fig.7: discolouration of the mat, total view

For comparison: in the upper area it is still a little bit lighter, here the waterlevel sinks due to evaporation, here bacteria do not settle, below one sees the darkened mat. During a waterchange, when the mat is dry, one sees that the colouration is from a brown organical film (fig.

Fig. 8: Colonization of the mat, detail

Those who want can place plants onto the mat. All plants wich are offerd to grow on driftwood or stones are acceptable, like javafern, javamoss or Anubias. For sure, others are fit aswell, one can test it out.
One can attach these plants with a toothpick or sew them with fishing line onto the mat. One can also place the javamoss on the edge of the mat and let it creep below. Fig, 9 shows how this looks in a 2.5 month old tank.

Fig.9 masking of a cornered Mattenfilter with plants, frontalview.

This filter is in a 60*30*30 cm tank (23.6*11.8*11.8 inches, 14.3 USG) and is overgrown with two javaferns "Windelov", a small Anubias and javamoss. Fig. 10. shows how it looks from above.

Fig.10.: masking of the cornered Mattenfilter, view from above

On this picture one also sees how the pump was attached: It was simply jammed in between the heater and the sidewall in two blocks of foamed plastic. This has the advantage that its vibrations are no longer at the sidewall, the pump works considerably fainter. If you look well, you see that the formerly blue blocks of foamed plastic have discoloured aswell, so here a bacterial fauna has established, too. With these small colonized blocks one can easily inocculate a new mat, then the bacterial fauna develops much faster than in a "nacked" tank. Especially if sand or gravel and other material in a new tank are brandnew.


One can make a cornered Mattenfilter with only little material and timely efforts. Due to is bowlike construction against waterpressure it gets a high stability. The guide rail of the two cablechannels increases this stability even more.
A mat is rather fast colonized by bacteria. The mat can be masked by epiphyts like javamoss, javafern or Anubias. So the mat is integrated optically in the aquarium within a few weeks completely. Nearly all technical devices can be hidden behind the mat. Thus, the rather large consumption of space of this variation of the Hamburger Mattenfilter (=HMF) is relativized. It can be integrated without problems in large and small aquariums alike.

End of original article
Original German language article:
Last updated October 16th, 2003.
spelling errors removed May 2006

How to use Olaf Deters calculations tools.
Until now, there are no translations I know of where one can simply enter his/her aquarium data and one gets results. So here is a step-by-step-process of how to use this site even if you don’t speak german:

First: We calculate in litres and centimetres. Please convert - if necessary - your tank volume from gallons to litres.: 1 gallon=4,546 litres, 1 U.S.gallon = 3.78 litres
Write down the volume of your tank in litres .

Second: Go to

for Q; enter the volume of your tank in litres
n is the number of times the tank should the circulated per hour. Leave it at 2
V is the flow of the water through the mat, it should be between 5 and 10 cm/minute . Leave it at 7.5
Press enter . What you will get is an area in squarecentimetres, to convert into squareinches: multiply with 0.155

Example: you have a 80 US-Gallons tank : that makes 80*3,78= 302,4 litres
Enter Q= 302.4 (mind the . )
Leave n = 2 and V = 7.5
Press enter, result is 1344 squarecentimeters
Multiply 1344 with 0,155 = 208,32 squareinches. This is the size your filtermat has to be.

[Third step: Abolish those crazy imp.units ]

If you want to find out if one of your existing pumps can be used for this method go to

For Volumen: enter again the volume of your tank in litres.
For n (the number the tank should be cycled per hour ) set 2 again

Press =

What you will get is a simple calculation V*n = Q and tells you the performance your pump should have. In our example with a 80 gallons tank (=302 litres) it is 604 litres per hour. If you now click on suche (=Search) you will get a list of pumps that have this size. If you click the two buttons to the left you can go up and down in this list.

Defining the radius of the bent mat (for the cornered Mattenfilter)
calculating the bent mat

Höhe Aqua(cm)
Pumpe (ltr/h)

Höhe Aqua = height aqurium in cm.To convert from inches multiply with 2,54
Pumpe (ltr/h) = the performance of the pump in litres per hour. If you only know the performance in gallons per hour: divide again by 4,546 (U.K.) or 3,785 (US), resp.
V in cm/minute is the speed of waterflow through the mat. Should be between 5 and 10. So leave it at 7.5

What you will get as result e is the radius of your mat .

Our 80 gallons (US) tank gave us (in the previous example) the need for a pump of about 604 litres per hour (= 159.6 gallons/hr)
The height of the tank is 20 inches. That makes 50,8 cm (enter in Höhe Aquarium)
For Pumpe (ltr/h) enter 604
V remains at 7.5
e = 16 cm that makes 6,3 inches

The distance from the corner of the tank to the middle of the cablechannel should be 6,3 inches

I would like to thank Olaf Deters and Jörn Carstens for their consent to use their articles.

Bye, Jörg


AC Members
Feb 23, 2007
Eastern Townships, Quebec
Very interesting. I am tempted to give that a try. Probably not on my 10gal, but when I have some spare cash to invest in a 75 or 90, I'll definatly have to look into this idea.

J double R

The Devil
Jan 13, 2007
Real Name
yes, an intriguing idea.. something i may try on the 75g someday after i get the stand built for the 100g.


AC Members
Jul 17, 2006
Innsbruck, Austrian Alps
you want to put in two "cornered" HMFs ? the idea is to let the volume of the tank pass twice per hour through the whole filter area of the mat.

So for a tank with a volume of n Gallons you should use a pump with a performance of 2n per hour. In your case: 2x55=110 gallons/hour, approximately. 10% more or less wont do much.
For my 300 liter tank i use one pump of 350 and one with 300 liters/h. Usually 2 smaller pumps are cheaper than one stronger one. Disadvantage is that now two cables come out instead of just one. In an other one i use an external Eheim Filter (without any substrate) as a pump. The most elegant way would be to do it without electrical (centrifugal) pumps and to use an "airlifter", a simple PVC tube with an inlet for air at its lower end. The air (from an ordinary aquarium air pump) ascends in the tube, creates a kind of upward current and the air-water mix is lifted up over the water level. If you place the outlet of the tube on the aquarium size of the mat, you get the most economic way for filtering your tank (CO2 will be outgassing faster, though). That way most breeders and professional fishkeepers do it here. I try to find some pictures.

To find out which size the filtermat should have:
(go to:
55 G = 210liter Q= 210 n

and finally a DIY construction with more pictures

Of course there are ways to increase the water/air ratio and to reduce the nois eof the bubbles, but that's too much for this thread (and i doubt that it is of interest...)
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