Ok, so some of you may of noticed in the Aquarium thread that I had some issues as to what to filter my new 6ft with effectively, as the base is a strange enclosed design with a stupidly small door. After some discussion here, and with another forum, and a lot of help from an extremely friendly NZer in the know-how, I decided to go with a corner Hamburg Matten Filter (HMF) setup. These filters have become extremely popular in Europe as they are low cost, don't take up room outside of the tank, extremely efficient biological filtration and require considerably less maintenance than other filters. Link to the original information page translated from German. In a nutshell, the original HMF is a large piece of foam, the size of the height x depth of the tank and around 5-7cm thick. 20-30ppi foam is generally best depending on what sort of effect wanted, I opted for 20ppi as it is the most commonly used. This large slice of foam is essentially wedged in the tank about an inch from one end of the aquarium, having some form of water movement relocate the water from the small side back into the tank. This can be achieved using either a normal power-head (as in the picture) or using an air powered uplift tube. I have opted for power-heads as they actually seem to be cheaper than the large L per M air pumps as well as I can easily ensure the correct amount of flow is achieved in each filter. As this version takes up an entire side of the tank, and is a fairly horrible eyesore especially on larger tanks, the design was conceived to change the filter from one flat piece spanning the entire width and height of the tank, to merely take up one corner of the tank. This also allows objects such as heaters and CO2 setups to be hidden behind the filter. This filter is different than a normal canister setup in that the optimal amount of water wanted to pass through the filter is 2-2.5 times the tank volume, and figuring out the size of the filter itself requires some maths. Now, I hate maths, most people hate maths, so I won't list mine here. Please see the original link or here for the list of formulae in working out the required filter size. Onto the build. This is the tank I am working with: It's a 6x2.2x2.2 According to my maths, I would require an extremely large corner filter, so I decided to split the load into two smaller filters on each side of the tank. I ordered my foam from Purely Poret in NZ, as the gentleman who runs the site has been more than accommodating in my many many questions regarding the filter. I worked out that each piece of foam would need to be approximately 60cmx30cm. Here are the pieces after being cut out of the 1mSq piece of foam I ordered. Next was figuring out how to hold the foam in place. Generally, the more professional corner filters are held in place using pieces of glass, or the more commonly used cable channel, however I was unable to track down any channel that was appropriate here so resorted to using 40x20 Aluminium L bracketing. Have since filled the tank and decided aluminium doesn't look very good in the tank, I've decided to re-do the bracketing with glass instead. Will update when it's complete.