There is provided an automated electrochemical device for generating a biocidal output solution, said device comprising: a flow-through electrochemical cell comprising an anodic chamber and a cathodic chamber for electrolysing an electrolyte to generate an anolyte solution and a catholyte solution; characterised in that the device further comprises: (i) a reservoir for storing catholyte; and (ii) a hydraulic circuit for recirculating catholyte from the reservoir to the anolyte on start-up of the cell, wherein input of catholyte of a compensating strength to the cell anodic chamber, is arranged so as to optimise the cell anolyte pH to produce a stable output solution at the start of the electrolysis process.