A method and system are disclosed for plating objects. At least one aspect associated with the object plating is monitored to determine the amount of at least one by-product created during the plating and/or the reduction in the amount of at least one plating component. Based on this monitored aspect, an adjustment is made to the flow rate of substances added to a plating cell and/or the flow rate of used plating substances drained from the plating cell. The used plating substances are purified to remove at least some of the by-product and then the purified plating substances are combined with at least one component before passing back into the plating cell to reuse at least some of the plating substances. The method and system could be used during the plating of semiconductor wafers with copper.