The Fine Kordon Mist-Air Air Stone pushes pressurized air through its minuscule resin bonded glass spheres as a way to aerate the aquarium. This process of aeration removes dangerous CO2 gases from the tank, while agitating the surface to promote the dissolution of oxygen into the water, improving the water quality for all aquatic life. Air stones are beneficial for both freshwater and saltwater tanks, and functional equally in both environments. This unit uses fine bubbles, but medium bubbles and coarse bubbles are also available depending on your porosity needs and desires. The primary way Kordon Mist-Air Air Stones differs from other brands is by using only resin-bonded glass spheres, which have a dramatically longer lifespan and don't suffer from the rapid disintegration that other common materials are known for, such as wood, fused-sand or porous plastic. With glass, there is a more consistent aeration as well as a significant lack of effort and maintenance on the part of the aquarist. This unit requires a moderate amount of air pressure, as the size of the bubbles are not large enough to have the desired aeration without additional pressure. The fine bubbles are highly sought after for saltwater and marine environments. The fine bubbles perfectly mimic the natural fog that occurs within the coral reef surge channels.