What brand protein skimmer?

[albert_dao]

I would size the skimmer according to your budget in that sense. If you're trying to be cost effective, size it according to the net volume after displacement. If you're blatantly able to afford a BK, size it to the gross volume (this assumes moderate to dense stocking).

Net vs. Gross volume calculations aren't a make or break calculation when it comes to skimmers unless we're talking about substantial displacements of water.

These kinds of calculations are more relevant to dosing regimes, eg. chemical additives, trace elements, probiotic methods, etc.