The Dennerle Bio CO2 fertiliser system Carbo Bio Style 120 supplies all freshwater aquariums up to 120 litres with vital CO2. The system is ready for operation in just a few steps. CO2 production starts after just 24 to 48 hours. A Bio CO2 diffuser specially designed for low operating pressure ensures fast, effective dissolution of the valuable CO2 in the aquarium water. Thanks to its modern, timeless design, the fertiliser unit also cuts a fine figure standing directly next to the aquarium. A pressure relief valve, pressure-resistant CO2 hose and solid hose fittings ensure a high level of operating safety. The Carbo Bio Style 120 CO2 fertiliser system is designed to be particularly sustainable: The stainless steel reaction tank is refillable and can be used for many years, the CO2 Constant gel consists of 100 % renewable raw materials.Dennerle BIO CO2 exploits the well-known fact that yeast cells are able to produce CO2 from sugar in the absence of oxygen. A problematic aspect is the