a strong base solution.  enough to make the mhrb solution turn blackish purple.  (for 1 cup of water id add a couple/few tablespoons... i typically just pour it in.. no need to be precise for this. )    ive gotten 10+ out of a kilo.. so im pretty sure im not leaving much behind.    useta do an a/b, but dropped the acid step as it is unneeded..  ime and in others experience..