The Reef Octopus Regal 300-EXT Recirculating Protein Skimmer is the flagship of the Regal line, rated from 500 to 740 gallons and built external to the sump for maximum air/water contact time. Water recirculates through the 36V VarioS-6S DC pump before draining back, producing drier, more concentrated skimmate than an in-sump body of the same rated capacity. Bioload capacity: 500 gallons (heavy), 620 gallons (medium), 740 gallons (light), excluding sump Setup: external, recirculating Pump: VarioS-6S variable-speed pinwheel pump, 36V, 5 power settings Control features: float switch input, 15/60-minute feed-pause modes, 0-10V third-party controller input For large reef systems where export quality matters as much as raw capacity, the 300-EXT is the top recommendation in the Regal lineup.Compatible replacement parts: VarioS-6S pump kits sized for the Regal 300 series.
