Filters, skimmers and biological know-how...
are requirements in marine aquariums; natural conditions are obtained, provided that there is a balance between the input and removal of food, waste and additives. The combination of equipment and know-how results in balance, where pollutants discharged into the water by some organisms (e.g. fish) are either utilized by other species (e.g. corals, small organisms) or removed by means of technical equipment (e.g. filters, skimmers).