Z's & P's don't require direct feeding, you can, but you don't have to. They derive most if not all of their nutrition via photosynthesis. Supplemental external feeding should only be considered a secondary, not a primary source/means of said nutrition. I wouldn't feed more than twice a week, there's simply no need to. I would definitely turn off any return pumps for an hour at least and leave some internal circulation to move the food about the tank.
MUcho Reef