The formation of biogas from biomass is a complex process with a multitude of variable process parameters. Stability of biogas production and production rate can be vastly improved by keeping these parameters close to their optimum. One possibility to achieve this is by use of additives. In Germany alone there currently are over 250 additives on the market which demonstrates the demand for optimisation of biogas plants. The effects of these additives are hardly investigated and can only be evaluated by costly, time consuming tests (eg continuous anaerobic digestion experiments). A new, fast and easy to handle method was developed to evaluate some of the effects of additives. To verify the method trace elements, organic acids, FOS/TAC, ions and cations were quantified. Three additives were tested: The addition of a commercial zeolite increased biogas production by 15%. Calcium carbonate increased performance by 8% after 16 days. No negative effect on biogas production could be observed for the addition of 0.03 and 0.06 gl-1 of iron (III) chloride, commonly used to reduce hydrogen sulphide concentration in biogas.