If you're looking for nitrate removal, you'll need to have a large, dedicated refugium with high lighting and fast growing macros such as chaeto, ulva, gracilaria, or caulerpa prolifera that you trim often.
Neptune is definitely a reefer if he shaves with calcareous algae...
But seriously, shaving brush is a lot like halimida in respect to water quality, it needs a good amount of NO3 and PO4 to sustain the ability to assimilate Ca and carbonates. Best housed with other algaes releasing Allelo's in the same volume of water.