Aquatic plants require co2 to grow and remain in optimal condition the fluval pressurised co2 kit ensures that optimal levels of co2 are avalible in the aquarium to maintain vigorous lush and vibrant aquarium plantsr this complete co2 system is perfect for planted aquariums from 57 litres to 151 litres and is simple to install and user the kit includesr one fluval pressurised co2 cylinder with a stand r an internal co2 diffuser r a visual bubble counter r a regulator valver tubing