The goal of the biogas production process is to obtain a yield of methane of at least 50%. The FOS/TAC value is an important characteristic to assess the status of the fermenter before costly problems arise. The new Eco Titrator from Metrohm allows the determination of this quotient in a fast, cost-efficient, and precise way. This white paper gives insight into why performing analytical monitoring of the biogas fermenter is of such enormous importance, and how the analysis is done in practice.