The exhibits at the National Aquarium in Baltimore display animals that live in fresh, brackish, and salt water. The Aquarium is not located close to a suitable source of any one of these types of water and therefore uses Baltimore City tap water.
Tap water is filtered to remove chlorine and other substances that are harmful to aquatic organisms.
This water is then used directly in freshwater exhibits such as the Allegheny Pond exhibit and the Shocking exhibit, or in the production of synthetic sea water. All the Aquarium's marine animals are maintained in synthetic sea water. Synthetic sea salt mixes combined with filtered fresh water provide a medium in which marine life can live by combining over thirty different elements in various amounts. There are many different formulas of synthetic sea salts, and research in refining and improving them is ongoing. From l98l to l99l the Aquarium used the commercial sea salt mix called Instant Ocean.