Five times the filtering power with higher absorptive Capacity than other premium brands Maximizes filter efficiency by helping to remove harmful toxins and ammonia from the aquarium water. Penn-Plax Pro Carb formula will keep your water clear for 4 to 6 weeks Pro-Carb leaves your water looking crystal clear and is safe for use in both fresh and saltwater fish tanks. Control pour spout and grip. pH- Stable; Phosphate Free