Carbon dioxide (CO2) is the basic plant nutrient and allows adjusting a slightly acidic pH value, as it is preferred by many plants and fish. The sera CO2-Start fertilizer system is easy to install and operate. It is ideal for the very widespread and popular smaller aquariums up to approx. 120 liters (31.8 US gal.). sera CO2-Start consists of an optically unobtrusive sera CO2 diffusion reactor and the corresponding sera CO2-Tabs plus. This convenient and uncomplicated CO2 fertilization system can be integrated into the aquarium even by beginners without any previous knowledge entirely without any problems.