I am interested repassivation kinetics in pure water (very low concentrations of ions). Most electrochemical techniques are simple to use when the electrolyte conductivity is rather high.

I wonder if a substance exists (e.g some kind of salt) that could be used to increase the water conductivity, but this substance (its ions) do not participate in the corrosion / passivation process? The metal I am interested in is stainless steel.