The Coralife Bio Balls Five Gallon Box will enable aquarists to maintain large biological loads in much smaller filter areas. The dramatic increase in surface area is achieved by the unique, geometric design of the smaller, one-inch bio-ball. One gallon of Coralife aquarium Bio-Balls, (approximately 1,125 balls), has a surface area of approximately 107.5 sq. ft. This surface area supports between 225 and 300 gallons of marine life. Also available in a One Gallon Box.