An apparatus for automatically generating a metal-containing electrolyte (e.g., an electrolyte containing Sn2+ ions and an acid) includes an anolyte chamber configured to house an active anode (e.g., a metallic tin anode), an anolyte, and a sensor (e.g., one or more sensors) measuring a concentration of metal ions in the anolyte; a catholyte chamber configured to house a hydrogen-generating cathode and a catholyte; and a controller having program instructions for processing data from the sensor and for automatically generating an electrolyte having metal ions in a target concentration range in the anolyte chamber. In some embodiments, the apparatus is in communication with an electroplating apparatus and is capable to deliver the generated electrolyte to the electroplating apparatus on demand. In some embodiments, a densitometer and a conductivity meter are together used as sensors, and the apparatus is configured to generate low alpha tin electrolyte containing an acid.