You add the additional 5 gallon bucket to the system to make it easier to change out the nuts. At about week 6, if you do not do this, you will destroy most of your root ball.
When you need to drain out all your nuts, you just empty out the 5 gallon bucket, open the valve and raise the plant bucket about 12 inches. To mix nuts, you do not have to lift the plant and that root mass, you just open up the 5 gallon bucket, and your water and nuts, then open the valve and raise the 5 gallon bucket about 12 inches. You will figure it out. If you do not do this. You will your next crop for sure.