Engineered to create superior water quality, the Fluval C2 Power Filter provides extensive 5-stage filtration-two mechanical, one chemical and two biological stages-for outstanding results. The Power Filter is designed to provide maximum surface area and optimum dwell times in all stages of the filtration process. Rigorous 2-stage mechanical filtration is performed by a thick layer of poly/foam that effectively traps large and fine debris. The foam slides out easily for quick cleaning.