Nyos OPUS G2 sizes at a glance
- OPUS G2 200: 43.9 gal display, 21.7 x 21.7 x 20.9 in, 9.3 gal sump. Shop the Pro-Line or Slim-Line.
- OPUS G2 250: 53.9 gal display, 27.6 x 21.7 x 20.9 in, 11.1 gal sump. Shop the Pro-Line or Slim-Line.
- OPUS G2 300: 69 gal display, 35.4 x 21.7 x 20.9 in, 14 gal sump. Shop the Pro-Line or Slim-Line.
- OPUS G2 440: 100 gal display, 49.2 x 21.7 x 20.9 in, 16.4 gal sump, 12 mm glass. Shop the Pro-Line or Slim-Line.
Every size shares the same 21.7 in (55 cm) depth and 20.9 in tank height, so the choice comes down to length, water volume and which cabinet you want.
Pro-Line vs Slim-Line cabinets
Both cabinet lines use moisture-resistant EN 312 boards with a scratch- and impact-resistant melamine finish and push-to-open doors, and both come in matt white or basalt grey. The Slim-Line matches the tank footprint exactly for the smallest floor space and the lower price. The Pro-Line is about 3.3 in longer and 4.1 in deeper than the tank, which adds storage room, and upgrades to BLUM 125° soft-close hinges, 38 mm solid doors, height-adjustable feet and a frame that hides the sand line and bottom silicone seam.
What comes with every OPUS G2
- Display tank with an external, hidden overflow and ultra-clear glass on the front and both sides
- Cabinet in your choice of line and color
- Ready-to-install PVC plumbing with an adjustable main drain valve and an emergency drain
- Five-chamber sump with a nylon filter sock
- Separate refill tank that holds about a week of RO water
Equipment to add
Nyos recommends a return pump of about 525 GPH (2,000 L/h) for every size; shop return pumps. For skimming, we pair a Nyos Quantum protein skimmer with each tank: the Quantum 120 for the 200 and 250, the Quantum 160 for the 300 and the Quantum 220 for the 440. Finish the system with reef lighting, powerheads, heaters and an auto top-off to feed from the refill tank.
Why the OPUS G2 stands out
The overflow box sits outside the glass, recessed into the deep blue back pane, so nothing interrupts the aquascape. Only transparent silicone is used in the display, there is no top bracing, and the 21.7 in depth leaves room for real aquascaping. Nyos builds the OPUS G2 in the EU, with cabinet wood from verified legal sources produced in FSC-certified factories.
