Aquatops Green Airstone Ball increases surface agitation and water oxygenation Helps release carbon dioxide build up For use in all aquariums. Increases surface agitation and oxygenation Helps release carbon dioxide build up Resists clogging and extends life of air pump Fits standard Airline tubing For use in all aquariums. Aquatops Sandstone air Stones feature a uniform pore structure which resists clogging; increases surface agitation and helps to oxygenate your aquarium water