What is a Wet Dry Filter?

 

Wet/dry filters are typically located beneath the aquarium. As the water drops to the wet/dry filter, it is agitated causing the water to mix with air. The aquarium water is then dispersed over the biological media chamber. The water level in the main part of the filter is maintained at 1/3 to 1/2 full, allowing a large part of the biological media to be exposed to air. After the water passes through the biological media, it flows through the bottom of that chamber into another part of the filter, referred to as the sump. In this open area of the filter, a protein skimmer, chemical medias, denitrator, or calcium reactor can be incorporated. The water pump responsible for returning the water into the aquarium is either located in the sump or next to the sump. The water pump is installed using either a bulkhead for in-line operation, or a submersible pump can be located directly in the sump. The biological filtration of wet/dry filters is far superior to the other filters because the amount of surface area within the biological media (bioballs), provides space for the beneficial bacteria to colonize in large numbers. Secondly, not only is the oxygen content of the water very high, the media is also directly exposed to the air which allows the bacteria to be exposed to even higher amounts of oxygen.