Crushed coral will help buffer your PH and enable you to use less of the powdered buffer.
the way to tackle nitrates is to add a refugium. If you're doing a sump, you can add a refugium to that. With a deep sand bed, LR
and Macro Algae, you're nitrate problem will be under control. Plus the skimmer and not over feeding. That's the biggest issue. All the brands say to feed daily or twice daily. It's about how much your fish need externally, versus what your tank provides. I think the benefit of CC outweighs the negatives if you are willing to plan it all out.