Flushing does nothing but starves your plants and effects yield. Ca, Fe, Zn, Mo, B, Cu, Mn are all immobile nutrients, meaning they cannot move from one part of the plant to another when there is a deficiency (which flushing causes), so in turn are not 'used up' when there is a deficiency. Why people spend 3-4 months caring more for their plants than themselves only to starve them at the end is beyond me.