I can't recommend using 120 volts, for same reason as I can't recommend using a hair dryer while you're sitting in the bath tub. In any case the applied voltage has very little to do with it. The perceived "industry standard" of thirty odd volts is really a hang over from the early Beck devices. Beck developed his Blood Cleaner first, which needed 30 volts to get the required current density. The CS maker was a later addition to the Black Box design so it too was set up to use the available 30v supply. In reality anything from about 2.5 volts will work in a constant current setup.
In a DC set up we want a cloud of positively charged silver ions to be emitted from the Anode(Positive) electrode and for them to be trapped in suspension by the opposite magnetic polarity of the water. At a given concentration the conductivity of the water increases to the point that silver ions begin to be plated directly to the Cathode (negative) electrode, where thay lose their positive charge, and form the grey sludge we're all familar with. You could make the argument that using a constant stirring device would speed up this process, by pushing more ions toward the cathode than would be the case with normal Brownian convection.
In an AC powered operation , where the polarity is switched constantly, this sludge is propelled and dispersed back into the water continuously. Mechanical effects of redispersal of plated out silver "sludge" from the cathode will occur at higher concentrations and especially at higher currents, resulting in much coarser, uncharged and therefore non-bioactive metallic silver particles floating about in your CS.