Posted by Shari Horowitz in Tropical Fish Hobbyist Blog on December 8, 2010 at 9:02 am
By Mike Hellweg
Over the past few years, as I’ve been visiting various clubs and getting to see other’s fishrooms, I’ve come across a “new” type of filter. They are easy to make, easy to use, and require little maintenance (all things I really like!). Apparently they’ve been popular for many years in Europe, appearing in the 1960s in Hamburg, Germany. The Germans call them Mättenfilters. When they migrated to other countries, this became “Hamburg filter” or simply “wall filter.” A few years ago, Stephan Tanner of Columbus, Ohio started importing the special rigid foam material to make them from Europe and selling it. It’s a bit different from sponge filter foam in that it is in sheets, it is able to stand upright, and water flows directly through it. He also came up with a great design that works very well and is very easy to make. At this point I believe he is the sole distributor in the USA.
Essentially, the filter becomes one of the short walls of the tank. This works really well in a fishroom setup when tanks are set up end on and one side becomes the back of the tank. These filters essentially disappear, as they are the entire back of the tank. The coarse foam material is also excellent for plants like Java moss, Java fern and Anubias to attach themselves and form a sort of living background. Behind the wall filter is a small area about ¾ to one inch or so in depth. This forms an in-tank settlement well where detritus can collect and be siphoned off. It also works as a great place to put the heater so it is out of the way. This is also where most of my overflows are located, hiding them and preventing even young fish from going over the wall. They give a clean, neat appearance to the entire tank, and make it very easy to catch fish when the time comes as there is no filter, heater or overflow fitting for them to hide around.
Essentially all you do is cut the foam to the dimensions of the tank, just a hair oversize so it fits snugly. This can be done with a straightedge and a sharp knife. Then cut a small hole in the center near the top (some folks cut a notch right at the top). This is where the return flow pipe will go. The return pipe simply consists of a length of PVC pipe, a 90° elbow, a piece of fiberglass soffit screen material (larger than window screen so it doesn’t clog over time), and a zip tie to hold the soffit screen piece to the end of the pipe. This keeps overly zealous fish from swimming down the pipe into the back area of the tank (loaches and danios especially LOVE to do this). On the plus side, this is where I’ve found baby Myer’s kuhli loaches Pangio myersi on a couple of occasions, including right at the end of the Breeder’s Challenge. It’s a nice safe place full of food.
Anyway, getting back to construction—drill a small hole in the top of the elbow to allow a piece of airline tubing to fit through it, and add an airstone in the uplift part of the tube. This will create a gentle current moving water from one end of the tank through the filter to the other end. The filter will become covered with nitrifying bacteria, but the flow will be slow enough that the filter won’t become clogged with detritus, needing to be cleaned regularly.
Stephan says they just need to be rinsed once a year, but so far I’ve had some going as long as 18 months and they have yet to need anything but a rotation of the airstone as it clogs and flow slows down. To clean the tanks, all I do is move a HOT filter from tank to tank once a month. Of course, water changes are also simplified as all I need to do is run water to the tank and it flows out the overflow and down the drain.