 Tetra External Filters are excellent choice fo a mid range aquarium filter. They are easy to use and offer great value compared to most other units.
The Tetra External Filter has been designed to be extremely easy to clean and has a lot of space for all different types of filter media. Each basket in the unit is designed for a different type of filter media. The bottom basket is used for Ceramic filter rings which are highly porous and designed hold beneficial bacteria which treat ammonia and nitrate. We recommend you use TetraTec CR Ceramic Filter Rings. You can also add a carbon pad to aid in the removal of toxic chemicals called the TetraTec CF Carbon pad. The next basket up is holds the bio balls which is another form of biological filtration they have a large surface area.
The next 2 baskets hold the filter foams and filter floss. The foams act in two ways. One is to filter out any solids and the second again is to give more bio filtering. If these get clogged then you need to clean them in tap safe water. Lastly there is the filter floss which is designed to remove as much solid gunk as possible. These are meant to be thrown away and can be easily replaced once they get brown with the TetraTec FF Filter Floss. | 
