Coralife aquarium Bio-Balls 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 300 balls), has a surface area of approximately 21.5 sq. ft. This increased surface area supports between 45 and 60 gallons of marine life. Available in a 1-gallon box and a beautiful reusable 5-gallon bucket