CO2 bio-fertilizer system for freshwater aquariums from 10 to 40 liters. It supplies aquarium plants with their main nutrient, CO2, for healthy and vigorous growth, which also helps combat algae. Very easy to assemble: mix biocomponents with water in the reaction bottle, connect the hose to the diffuser - done. Natural: CO2 production through a biological fermentation process. Economical: 40 days of consistent CO2 production through an immediate and long-lasting buffering system. The biocomponents can be purchased individually in refill packs. No need for a pressurized CO2 bottle. The system operates solely through a biological process.