Coralife Bio-Balls 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 Bio-Balls, (approximately 225 balls) has a surface area of approximately 21.5 square feet. This increased surface area supports between 45 and 60 gallons of marine life.