Skimmer wise I don't think brs carries anything larger then 800 gallons and 2' tall so I would need 2-3 of those maybe.... There won't be any fish so I'm thinking I can get away with the low end with no issues at all. As for external pumps I'm looking at the reeflo barracuda/hammerhead hybrid 6000/4590 external pumps right now to be the heart of the system. Maybe one per spillway and one for all the frag tanks.