• 90 L sump — the largest in the range — more usable chamber space for a calcium reactor, dosers or a bigger skimmer than the 300 or 350 allow.
• Thicker side glass at this size — 15 mm sides against 12 mm front and bottom, sized up to handle the extra water pressure of a 433 L system.
• Drilled central overflow with removable weir comb — quiet downflow into the sump, no external overflow box on the back panel.
• REEF-SPEC sump with dedicated chambers — mechanical filtration compartment, adjustable-height skimmer chamber, bubble trap and RO reservoir space.
• Marine-spec plywood cabinet in matte black — moisture-resistant, on adjustable levelling feet, with quick-release door hinges.
• Metric and USA bulkhead fittings included — Red Sea's own pumps or aftermarket equipment plumb straight in.

Included: the drilled display aquarium, the built-in overflow with weir comb, the REEF-SPEC sump (mechanical filtration compartment, skimmer chamber, bubble trap and RO reservoir space), the black cabinet, plumbing with metric and USA bulkhead connectors, and starter micron filter socks.

Not included: return pump, protein skimmer, lighting and auto top-off (ATO) system, and a heater. At this size those alone can add close to what the base system costs — plan the full equipment list before ordering rather than after. For a factory-fitted pump, skimmer, lighting and ATO, look for a Reefer MAX instead; this listing is the standard Reefer G2+.

All three sizes share the same REEF-SPEC sump layout and the same bring-your-own-equipment approach — the difference is footprint and water volume. The 425 is the largest, with the deepest sump for reactor and dosing gear and the only model with reinforced 15 mm side glass. The 300 is the compact option; the 350 trades some depth for a wider, shallower display at a similar total volume.

The display footprint is 120 × 60 cm, with a total system height of 142 cm including the cabinet — the extra 10 cm of depth over the 350 means it sits proud of a standard stud wall, so measure clearance behind as well as the floor footprint. At 433 L total system volume, the water alone weighs around 433 kg; glass, sump, cabinet, substrate and rock add meaningfully more on top of that. Red Sea doesn't publish a total filled weight for this model, and at over 400 L this is exactly the size where floor loading stops being a formality — get a builder or structural engineer to check the point load before installing on anything other than a ground-floor slab.

Suitable for an experienced reefer planning a heavier bioload or a dosing-intensive system, where the extra 21 L of sump space over the 350 genuinely matters. Suitable if you're happy to source and budget for a return pump, skimmer, lighting and ATO on top of the base price. Not suitable as a first tank if budget is tight — the 300 gets you into the same REEF-SPEC ecosystem for meaningfully less, with less equipment to buy around it.

A DC return pump with enough headroom for a full sump — the Red Sea ReefRun G2 6000 DC Pump or the larger ReefRun G2 8000 if you're running a reactor loop off the same sump. A skimmer sized to the sump's chamber — the Red Sea Reefer Skimmer 300 PSK600 as a starting point, sized up if you're stocking heavily. Lighting such as the Red Sea ReefLED 90 across the 120 cm span. And the Red Sea ReefATO System to automate top-offs on a system this size, where manual topping up daily gets old fast.

Covered by Red Sea's manufacturer warranty against manufacturing defects — 3 years as standard, extendable to 5 years at no extra cost by registering the system with Red Sea after purchase, in addition to your rights under Australian Consumer Law. This is the heaviest of the three systems: expect palletised freight with a delivery dock or ground-floor drop-off, and confirm a two-person lift and clear access before delivery day.

Does the Reefer G2+425 come with a return pump, skimmer or light?

No. This listing is the aquarium, overflow, sump, cabinet and plumbing only. Return pump, protein skimmer, lighting and ATO are sold separately.

Why is the side glass thicker on the 425 than the 300 or 350?

At 433 L total volume the water pressure on the side panels is higher, so Red Sea specifies 15 mm side glass on this model against 12 mm on the smaller two.

Is the 90 L sump enough for a calcium reactor and dosers together?

It's the largest sump in the range and generally has room for both, but check the specific footprint of your chosen reactor and dosing pumps against the chamber dimensions before buying, since exact clearance varies by brand.

How much heavier is the 425 than the 350 once it's running?

Water weight alone is around 433 kg against 342 kg for the 350 — roughly 90 kg more before equipment, rock, sand and livestock are added.

Do I need engineering advice before installing this one?

Strongly recommended unless it's going on a ground-floor slab. At over 400 L of water alone, plus glass, sump, cabinet and rock, this is not a load to guess at.