Check the listing for details. 300 pcs 1.25" Bio Balls Aquarium Fish Pond Filter Media FREE MEDIA BAG. Condition: New. Listed at 28.99 USD. Description : Clarify your water naturally and cultivate beneficial bacteria with these Polypropylene Bio-balls! Bio balls with their immense surface area per square inch serve as great hosts to beneficial bacteria in aquatic biological filtration systems. They promote gas exchange and increase dissolved oxygen levels, then filter the water as the bio-balls combine with organic waste to dissolve it. Feature: · For use in fresh & saltwater aquarium and ponds. · Free media bag for easy handling · BIO-Balls do not require replacement unless damaged or destroyed · In the event of excessive buildup, you may gently rinse with water from an established aquarium, if desired DIMENSION: Diameter of bio ball: 1.25 inch Size of media mesh bag: 16x11.5 inch INCLUDES: 300 pieces of bio balls in 1 mesh media bag. Approx 2.5 Gallon total.