The influence of Ag-Cu ions on natural biofilms of variable ages: Evaluation of MIC

•Ag-Cu ions changed the biofilm structure and led to shedding of the biofilm.•As the exposure time of the biofilm to Ag-Cu ions increased, the amount of carbohydrate in the EPS decreased.•Ag-Cu ions accelerated the corrosion of galvanized steel.•Ag-Cu ions concentrations suggested by EPA is not recommended to prevent MIC problems in cooling tower systems.