Aqua-Tech Activated Carbon Aquarium Filter Water Cleaner, 9 oz Aqua-Tech Activated Carbon removes odor and discoloration from aquarium water. Use this carbon in all aquarium filters to keep your tank looking clear and clean. First, place carbon in media container or mesh bag. Rinse carbon with tap water and then place media container in filter. Finally, remember to replace media container every two to four weeks. You can use this fish water cleaner in virtually all models of aquarium filters. This product is simple and effective, plus it's safe to use. Activated carbon is also useful for home cleaning and deodorization, plus many other applications around the house.