To start with carbon dioxide fertilization Carbon dioxide (CO2) is the primary nutrient for plants and allows for a slightly acidic pH value, which is preferred by many plants and fish. The sera CO2-Start fertilization system is easy to install and operate. It is ideal for small, common, and popular aquariums up to about 120 liters (31.8 US gallons). The sera CO2-Start consists of a visually unobtrusive CO2 reactor from sera, along with sera CO2-Tabs+ tablets. This convenient and simple CO2 fertilization system can be integrated into the aquarium even by beginners without any prior knowledge, completely without any Disorders.