Sump filters are generally used by advanced aquarists who maintain large tanks but this should not deter you from utilizing one for your show tank set up.

Sump filters, although commercially available, are usually home made. They consist of a series of containers (sumps), normally small aquariums, each of which are filled with a range of media to satisfy different filtration functions. Water is either pumped electrically, drained via hole in the base of the tank, or allowed to over flow from the aquarium into the first sump sited below the aquarium. In a similar manner, water is transferred through each sump, filtered and then electrically pumped back to the aquarium.

The sump filter provides many advantages. Firstly its size is only restricted by the space available under the aquarium thus the filter can have a vast capacity and require less maintenance. Secondly the filter media can be tailored exactly to ones specific requirements. One may choose to have a course mechanical pre-filter, a finer grade secondary mechanical filter, a section containing ceramic rings for biological functions or water polishing and a chemical section to alter pH or hardness. Many aquarists also use one sump to house the aquarium heaters or aeration devices thus removing any unnatural objects from the tank or even utilise this sump as an additional grow on tank for fry. Other aquarists I know even harvest algae in one sump to help reduce nitrates.

The fact that sump filters are large and remote form the tank allows the aquarist to perform all filter maintenance without disturbing the tank. Entire sections of the mechanical filtration can be also cleaned at one time without affecting biological colonization. Additionally, because the water level in the sump can be controlled, water changes can be performed over a longer period of time without causing stress to the fish.