Red Sea REEFER G3 Aquarium System 300

• Rimless ultra-clear display – 247 L display volume behind 12 mm front and side glass, with a low-profile internal overflow so there's no visible overflow box breaking the sightlines.
• ReefATO+ auto top-off included – Red Sea's electronic top-off system, with temperature monitoring and leak detection, comes standard on G3 rather than as an upgrade.
• G3 redesigned plumbing – fewer sharp 90° bends and a new ReefGate flow valve are built to deliver more water flow than the equivalent G2 model, with quieter, more precise drain control.
• Purpose-built 57 L glass sump – pre-glued plumbing and a mechanical filtration chamber with 225-micron mesh, ready for a ReefMat fleece roller (sold separately).
• Marine-spec cabinet – laminated plywood with epoxy-painted doors, stainless steel hinges and levelling feet, in the colour shown on this listing.
• 301 L total system volume – the figure to use for salt mix, dosing and medication calculations, not the smaller 247 L display-only figure.

• REEFER G3 300 aquarium, rimless ultra-clear glass with internal overflow
• Marine-spec cabinet, in the colour shown
• Glass sump with pre-glued plumbing and ReefGate flow valve
• ReefATO+ auto top-off system, with temperature monitoring and leak detection
• Mechanical filtration chamber with 225-micron mesh filter

• Return pump
• Protein skimmer
• Lighting
• ReefMat fleece roller filter
• Heater
• Salt, substrate, aquascape and livestock

This listing is the base G3 platform: tank, sump, cabinet and auto top-off, with your choice of pump, skimmer and light fitted afterwards. Red Sea's REEFER MAX line ships as a complete kit, with a pump, skimmer and lighting already fitted, at a higher price point. If you want a system that's ready to run on day one, check a MAX model rather than assuming this one includes it.

The 300 is the smallest footprint of Red Sea's current G3 line-up: 90 × 57 cm, a practical fit for a first sumped reef system or a space-limited room. Step up to the 350 for a longer footprint at a similar depth, or to the S-550 for meaningfully more display volume without gaining length.

Red Sea redesigned the plumbing for this generation, cutting the number of sharp 90° bends and fitting a new ReefGate flow valve for precise, near-silent control over the drain rate. Every G3 model, including the 300, now ships with the ReefATO+ electronic auto top-off as standard, where earlier REEFER generations needed it as an add-on.

Suitable for: reef and marine keepers who want a rimless drilled system with a proper sump, and are sourcing their own return pump, skimmer and lighting to suit their bioload and budget.

Not suitable for: anyone who wants a single purchase that includes a skimmer, return pump and lighting – that's Red Sea's MAX range, not this listing. Budget for that equipment before you commission the tank.

Red Sea's REEFER range carries a manufacturer's warranty of 3 years standard, extendable to 5 years total with registration within 90 days of purchase – provided in addition to your rights under Australian Consumer Law. Mains-powered components, including the ReefATO+ unit, run on 240 V / 50 Hz Australian supply. Red Sea does not publish an empty or filled weight for this system; as a floor-loading guide, the water alone in a full 301 L system weighs around 301 kg, before the glass, cabinet, sump, aquascape and livestock are counted – check your floor's load rating before committing to a spot, particularly upstairs or over an unsupported span. This is a large glass and cabinet item delivered on a pallet; the cabinet requires assembly.

• Red Sea Reefer DC Skimmer 300 – a protein skimmer sized to this sump; check your bioload before stepping up to the 600.
• Red Sea Salt 20kg Refill Box – mixes enough saltwater for water changes and topping up a system this size.
• Red Sea Seawater Refractometer – for checking salinity before the tank goes live.
• Red Sea Calcium Pro Testing Kit – reef dosing starts with knowing where your parameters sit.

Does the REEFER G3 300 include a return pump or skimmer?

No. This listing is the aquarium, sump, cabinet and ReefATO+ auto top-off only. A return pump and protein skimmer are sold separately, so you can size them to your stocking plan.

What does the 301 L figure on this listing mean?

It's the total system volume – display plus sump combined. Use that figure, not the 247 L display-only volume, for salt mix and dosing calculations.

Does it come with lighting?

No. Choose a fixture sized to the 90 × 57 cm footprint separately.

Is the ReefATO+ auto top-off really included, or is that an upgrade?

It's included as standard on every G3 model. Earlier REEFER generations needed it as a separate upgrade kit.

How much does a full system weigh, and will my floor take it?

Red Sea doesn't publish a tank or cabinet weight for this model. The water alone in a full 301 L system weighs around 301 kg – worth checking your floor's load rating for a system this size, especially upstairs.

What's the difference between this and a REEFER MAX?

Red Sea's REEFER MAX line applies the same rimless build with a pump, skimmer and lighting already fitted. We don't currently stock a G3 MAX at exactly 301 L, but the Max 425 G3 shows what a MAX kit includes if you'd rather buy pre-equipped.