Aqua-Tech 5-15 Aquarium Power Filter to Clean and Maintain Tanks helps to remove the toxic ammonia and nitrites from your aquarium s water. It provides filtration in three stages which will keep your fish healthy and water clean over time. Aqua-Tech Aquarium Filter Cartridges help to clean out the dirt and dust when water passes through it. In the second stage the activated carbon present in this fish tank power filter helps to remove dissolved waste and cleans water which is full of odor. In the final stage the filter provides extra surface area allowing helpful bacteria to grow. This bacteria eliminates the harmful ammonia and nitrates from the water which will protect your fish against these toxins. This fish tank power filter is available in four sizes. It also provides filtration for aquarium sizes that range from five to 60 gallons of water. It s very important to keep replacing the filter cartridge every month for continued excellent results.