Aquatic plants require CO2 to grow & remain in optimal condition. The Fluval Pressurised CO2 kit ensures that optimal levels of CO2 are avalible in the aquarium to maintain vigorous, lush & vibrant aquarium plants. This complete CO2 system is perfect for planted aquariums from 57 litres to 151 litres & is simple to install & use. In the kit is one Fluval Pressurised CO2 cylinder with a st&, an internal CO2 diffuser, a visual bubble counter, a regulator valve & tubing.