Macdermid Iridite 1A OD - Rainbow finish

We are plating aluminum with electroless nickel and cad, we are using a metex cad after the cad and then going to the chromate olive drab Iridite 1A OD, and the parts are coming out with a rainbow effect, how can we get rid of the rainbow effect, someone suggested to add 35% hydrogen peroxide to the metex cad.  Does anyone have another solution?