Aqueon Shrimp Essentials replaces important trace minerals that are vital to invertebrates and are removed through chemical filtration as well as used by individual shrimp in the aquarium. Shrimp and freshwater crayfish have exoskeletons that require additional nutrients for biological processes like molting and osmoregulation. These nutrients help the crustaceans cast off their old exoskeleton and harden the new one. Use when preparing tap water for new aquariums, performing water changes or when adding water due to evaporation. It is helpful to remove chemical filtration, such as carbon or other resins, for a brief time when adding to prevent absorption and help optimize available nutrients..