Methods and systems for acid regeneration of ion exchange resins are disclosed. Acid resins designed for use in a variety of cleaning application using a water source use a treated, softened, acidic water source according to the invention. Various methods of using the softened acidic water generated by acid regenerate-able ion exchange resins are disclosed to beneficially reduce spotting, filming and scale buildup on treated surfaces, reduce and/or eliminate the need for polymers, threshold reagents and/or rinse aids, and using protons generated in the acidic water effluent for triggering events useful in various cleaning applications.