I may be strong on the citric, but 3-4 drops of soap can leave me with with too much foam... I'm sure that amount varrys by the concentration level of the soap...
heard the Simple Green types of soap work well... btw... I don't necessarily use a whole lot of water... maybe a quart or so in my RCBS Sidewinder, with 2.5 lbs of pins, & 200-250 pistol cases
however, the cleaning concentration is not going to effect what has already happened to the case while in "the elements" if the case is black, it's already had some galvanic corrosion... perhaps using enough citric to cause them the pinkish cast, will allow them to be better identified if they fail before the others in the batch ???
In life you either make dust or eat dust...