32 Sponge loop filter

The sponge loop filter is a biofilter. In a light-protected filter, the aquarium water flows with constant flow in a largely laminar manner through a growth body with an extremely high interstitial volume. Cryptic (hidden-living) sponges settle on the carrier body over time. In reef aquariums with extremely little growth area/living rock, the sponge loop filter can be a useful system for stabilizing the biolgy.

Sponge loop refers to a process in tropical and arctic coral reefs where corals regularly release slimes that rapidly dissolve or break down into tiny particles in the water. These substances cannot be absorbed by most organisms. Sponges, however, use their metabolism to convert this material into particulate organic carbon (POC). The POC can now be taken up and utilized by filter feeders. The reef system thus becomes more effective and stable.