NOVELTY - Electrolysis system for maintaining a concentration range of an electroreducible metal species during electrolysis, comprises a sensor for sensing the concentration, and an exchanging mechanism for exchanging solution (110) between containers (114) responsive to the sensed concentration.    USE - For maintaining a concentration range of an electroreducible metal species during electrolysis, useful for metal particles producing system for producing metal particles (claimed), for use as feedstock for laboratory and industrial processes, and for use in refuelable and regenerative metal/air fuel cells.    ADVANTAGE - The invention optimizes the quality of metal particles produced through electrolysis.    DETAILED DESCRIPTION - Concentration maintaining system for maintaining a concentration range of an electroreducible metal species during electrolysis, comprises a first container for containing a body of a solution in which a metal is at least partially dissolved; a second container in fluid communication with the first container and containing a second body of the solution, the dissolved metal in the second container having a concentration; an electrolyzing mechanism for electrolyzing the metal, and at least partially immersed in the second body; a sensor for sensing the concentration; and an exchanging mechanism for exchanging solution between the containers responsive to the sensed concentration. An INDEPENDENT CLAIM is also included for metal particles producing system (100) for producing metal particles by electrolysis, comprising a first container for containing a body of a solution in which a metal is at least partially dissolved; a second container in fluid communication with the first container; a discrete particle electrolyzer at least partially immersed in the second body, comprising an anode (104) at least partially immersed in the second body, a cathode (106) having electrically coupled active zones (102) separated from each other at the cathode surface by an insulator, each active zone formed of an electrically conductive material, the cathode at least partially immersed in the second body; a channel for directing the solution including the dissolved metal between the anode and active zone(s) of the cathode; voltage mechanism for applying an electric potential between the anode and cathode to cause metal particles to form on active zone(s) of the cathode; a sensor; and circulating mechanism for circulating the solution from the first and second containers through the channel responsive to the sensed concentration, where the concentration may be maintained within predetermined limits during electrolysis.    DESCRIPTION OF DRAWING(S) - The figure illustrates a metal particles producing system through electrolysis, including a lateral view of electrolyte flow across the cathode surface.    Metal particles producing system (100)    Active zones (102)    Anode (104)    Cathode (106)    Pump (108)    Solution (110)    Containers (114)