+1 on chaeto only. The grape caulerpa grows like crazy and IME does a better job with nitrate uptake, but once a tiny piece makes it into your display, it's there forever and will likely spread. Then there's the sexual meltdown that can really make a mess.
I use chaeto only now, the grape caulerpa has been bleached off of my DT live rocks twice -- I really hope it's gone. Healthy chaeto ball + beefy skimmer = undetectable nitrates and phosphates in my bare bottom.