Aqua One BioNood Ceramic Noodles are a mixture of Biological and Mechanical filtration. It creates the ideal environment for beneficial bacteria to easily grow for optimal biological stability. The combination of this media is excellent at naturally attacking waste for both freshwater and saltwater aquariums, in all types of filters (canister, internal and wet dry) without altering water flow. This works because the bacteria catch and digest excess food and faecal matter; thus, removing potential toxins from this waste. These Ceramic Noodles do not expire; they are reusable by rinsing off excess waste with your existing aquarium water in a bucket, and returning the Ceramic Noodles back into your filter. Follow set up instructions on the label for optimal results. Available in a 600 g, 250 g, or 1.2 kg container.