can you reuse nutrients somehow with rockwool?

I hand water my rockwool cubes, which the excess water goes into 5gallon buckets, which i usually dispose of or water the plants outside with. My feeding schedule is FFWFFWW. So I mix nutrients 4 days a week. Is this right or am I wasting a lot of nutrients? Sorry I'm kind of a newb to this. Wondering if the second day of feeding I can take the drained water and reuse it so that I only mix nutrients twice a week.