The all-natural large-water AquaSphere®PRO is a 30-day, time-released system that sinks to the bottom of your water and introduces beneficial bacteria, which reduces excess nutrients and breaks down organic matter that clouds water. The spheres are biodegradable, making cleanup safe and easy. Large water AquaSpherePRO 6-inch spheres are designed with a higher concentration of bacteria and are to be used in larger bodies of water and allow our customers to treat their water more economically. Healthy Ponds recommends using multiple spheres, placed at various locations in the body of water, to achieve the best results.