Goldfish Station

These filters hang on the outside of the tank, usually in the back of the tank so as not to interfere with the view. Usually they are powered by their own motor; however, there are some that will use an air pump to power them. The filter operates on the same premise as the previous one. Water passes from the tank through an upside-down U-shaped tube into the filter. There it goes through the same series of wadded media as in the box filter before it is pumped back out into the tank.

These are among the most powerful filters available. They are not better in terms of filtration media, because they use the same materials. They are better because these types of filters tend to move more water faster.