Penn Plax Pro-Carb Z Contains Activated Carbon and Zeolite for Crystal Clear Remove toxins, harmful chemicals, and odors from your aquariums water with our specially formulated Pro-Carb Z filter media. Pro-Carb Z is the ideal blend of Pro-Carb and Pro-Z laboratory activated carbon and ammonia-removing zeolite crystals. Maximizes filter efficiency by helping to remove harmful toxins and ammonia from the aquarium water. Pro Carb Z leaves your water looking crystal clear and is safe for use in both fresh and saltwater fish tanks.