A method of rapid biochemical cycling of aquariums using naturally preserved granular marine substrate material, such as sand or aragonite, to rapidly denitrify the aquatic environment and to establish biochemical conditions that are favorable to the survival and viability of fish, crustaceans, invertebrates, and other marine aquatic life. The method includes the steps of harvesting and packaging marine sand such that marine microorganisms, in the form of biofilm attached to the sand, are preserved with an optimal amount of water and air in retail packaging specifically dimensioned and configured for maintaining ammonia oxidizing bacteria in a state wherein the bacteria are capable of metabolic and physiologic activity after prolonged periods at room temperature. Harvesting and packaging marine microorganisms according to the disclosed method allows for widespread distribution to consumers through conventional retail sales channels. Rapid biochemical cycling of an aquarium is achieved by introducing the contents of the packaging into an aquarium whereby marine microorganism biofilm instantly contributes to establishing a healthy aquatic environment by reducing harmful ammonia levels and through denitrification.