Red Sea Reefer 300 G3 - Black Cabinet

The Red Sea Reefer 300 G3 - Black Cabinet is a premium 300 litre / 79.3 gallon reef-ready aquarium and cabinet system built for aquarists who want a deeper 90 cm REEFER G3 display with Red Sea’s upgraded sump-based infrastructure and a clean black marine-spec cabinet.

This base REEFER G3 system is designed as a high-quality foundation for a custom reef build. It includes a rimless ultra-clear glass aquarium, black marine-spec plywood cabinet, REEF-SPEC sump, ReefMat-ready mechanical filtration chamber, pre-assembled plumbing, ReefGate precision valve, central overflow with removable surface skimmer, curved dual return nozzles, and integrated ReefATO+ smart top-off control. Lighting, return pump, protein skimmer, heater, wavemakers, rock, sand, salt, livestock, and optional automation accessories are selected separately so the system can be built around the reef you actually want to keep.

Red Sea REEFER 300 G3 Black Reef System

• Deeper 90 cm reef platform: The REEFER 300 G3 keeps the useful 90 cm display length of the 250 while increasing front-to-back depth to 57.5 cm, giving aquascapers more room to build a dimensional reef.
• 300 litre total system volume: The larger water volume improves stability and gives more flexibility for coral planning, fish selection, nutrient control, and long-term reef growth.
• Black cabinet presentation: The black marine-spec plywood cabinet creates a sharp, modern, high-contrast look that helps coral colour and aquascape shape stand out.
• Base-system flexibility: This REEFER package leaves major hardware choices open, making it ideal for customers who want to choose their own light, pump, skimmer, heater, flow, dosing, and control equipment.
• Rimless ultra-clear display: The REEFER 300 G3 remains in Red Sea’s rimless G3 range, giving the aquarium a clean modern profile with smooth beveled-edge styling.
• Strong custom reef foundation: The 300 is a practical step up for hobbyists who want more volume and depth than smaller compact reef systems without moving into a very large aquarium.

Deeper Ultra-Clear Display and Reef Layout Space

• 246 litre display volume: The display provides meaningful room for coral colonies, selected reef fish, rock structures, sand zones, and open swimming space.
• 90 x 57.5 x 55 cm dimensions: The wider depth makes it easier to create island aquascapes, sloping structures, caves, negative space, and front-to-back coral zones.
• 12 mm glass specification: The REEFER 300 G3 is listed with 12 mm front, side, and bottom glass for its rimless display format.
• Ultra-clear viewing panels: Low-iron glass improves clarity and reduces colour distortion so coral fluorescence, fish colour, and aquascape detail show more cleanly.
• Open-top aesthetic: The rimless format keeps the aquarium looking refined and gives practical access for aquascaping, feeding, coral placement, and maintenance.
• Hidden sump equipment: Filtration and most support equipment are housed inside the cabinet so the display remains clean and reef-focused.

G3 Flow System and ReefGate Control

• Hydrodynamically improved plumbing: REEFER G3 systems use redesigned flow architecture for improved water circulation and efficiency.
• Silent downflow design: The enlarged rectangular downflow inlet helps reduce turbulence and operating noise.
• ReefGate precision valve: The high-precision gate valve allows fine drain-line tuning for stable, near-silent overflow and sump performance.
• Surface-skimming overflow: The central overflow includes a removable surface skimmer to help remove surface film and improve gas exchange.
• Curved dual return nozzles: Improved return outlets help spread water back into the aquarium more effectively than straight returns.
• Pre-assembled plumbing: The factory-designed downflow and return plumbing simplifies setup and gives the system a clean under-cabinet water path.

REEF-SPEC Sump and ReefATO+ Stability

• 54 litre sump volume: The in-cabinet sump provides dedicated space for mechanical filtration, return equipment, skimming, media, probes, and optional filtration upgrades.
• ReefMat-ready chamber: The mechanical filtration section includes micron socks and media cups and is designed for optional Red Sea ReefMat installation.
• Integrated ReefATO+: The included smart top-off system helps stabilize water level and salinity while adding temperature monitoring and leak detection.
• Flexible equipment bay: The sump layout gives reef keepers room to plan skimmers, reactors, media, refugium-style nutrient export, dosing lines, and monitoring accessories.
• Cleaner maintenance workflow: Filtration equipment is consolidated below the aquarium, making regular service easier than a rear-chamber-only system.
• Future-ready Red Sea ecosystem: The system pairs naturally with optional ReefRun pumps, ReefLED lighting, REEFER skimmers, ReefMat, ReefDose, ReefWave, and ReefBeat-connected devices.

Red Sea Reefer 300 G3 Black Specifications

• Total system volume: 300 L / 79.3 gal.
• Display volume: 246 L / 65.0 gal.
• Sump volume: 54 L / 14.3 gal.
• Display dimensions: 90 cm L x 57.5 cm W x 55 cm H / approx. 35.4 x 22.6 x 21.7 in.
• Total height with cabinet: 142 cm / approx. 55.9 in.
• Glass thickness: 12 mm front glass, 12 mm side glass, 12 mm bottom glass.
• Display format: Rimless ultra-clear glass aquarium.
• Cabinet: Black marine-spec plywood cabinet with leveling feet.
• Filtration: REEF-SPEC sump with mechanical chamber, micron socks, media cups, ReefMat-ready layout, and ReefATO+.
• Recommended return pump: Red Sea ReefRun G2 6000, sold separately.
• Recommended lighting: Red Sea ReefLED G2 115, sold separately.
• Recommended ReefMat: Red Sea ReefMat 500, sold separately.

Application Notes for the REEFER 300 G3

• Best use: Ideal for saltwater reef aquariums, LPS reefs, soft coral displays, carefully planned mixed reefs, and custom sump-based coral systems.
• Depth advantage: The 57.5 cm width gives aquascapers more room for open sand, layered rockwork, coral spacing, and natural reef structure.
• Equipment planning: Add a suitable return pump, protein skimmer, lighting, heater, wavemakers, and testing equipment before starting the reef.
• Lighting flexibility: The recommended ReefLED G2 115 is sold separately, and lighting should be selected around coral goals and coverage preference.
• Flow planning: Add wavemakers based on coral type, rockwork density, and desired flow pattern.
• Not included: Lighting, return pump, protein skimmer, heater, wavemakers, livestock, rock, sand, salt, optional ReefMat, dosing equipment, and test kits are sold separately unless otherwise stated.

Red Sea REEFER G3 Series Video

Setup and Installation Notes

• Assemble and level the cabinet: Build the black cabinet according to Red Sea’s instructions and confirm it is level before placing the aquarium on top.
• Plan equipment before filling: Choose the return pump, skimmer, heater, lighting, and flow pumps before adding saltwater or livestock.
• Install plumbing carefully: Confirm the overflow, downflow, ReefGate valve, return plumbing, sump, and ReefATO+ components are correctly installed.
• Leak test with freshwater: Run the system with freshwater first to confirm plumbing seals, sump operation, and return flow.
• Tune the ReefGate slowly: Make small valve adjustments until the overflow and sump run quietly and consistently.
• Use RO/DI water: RO/DI water is recommended for salt mixing and evaporation top-off.
• Cycle before stocking: Establish biological filtration before adding fish or corals, then stock gradually to maintain stability.

What’s Included

• Ultra-clear rimless glass aquarium
• Black marine-spec plywood cabinet with leveling feet
• REEF-SPEC sump with mechanical chamber, micron socks, and media cups
• Pre-assembled downflow and return plumbing with ReefGate precision valve
• Central overflow with removable surface skimmer
• Curved dual return nozzles
• Integrated ReefATO+ sensors and controller

Shipping Notes

• This item is exempt from our free shipping policy.
• To avoid delays, please order Red Sea aquariums by themselves. If you are wishing to order multiple things, please place two separate orders: one for the aquarium and one for the rest of your products.
• Please call for a shipping quote if ordering from NWT, YK, or NUN.
• All Red Sea aquariums are brought in and shipped out on an as-ordered basis. The average turn-around time to ship an aquarium to you is two business days, except where noted below.
• All shipments outside of the Vancouver area are shipped via trucking company with residential and power tailgate delivery, and are fully insured.
• Tanks ordered within BC and, in some circumstances, Alberta may take an extra 5-10 business days to process. Systems ordered from Alberta and east of there usually ship within two business days direct from the distributor in Ontario.
• If you are ordering for pick-up from our store, please select in-store pickup to avoid delivery charges. You will be notified when the tank arrives, usually within 5-10 business days.
• Red Sea Max S Series aquariums are always special order and will take from 3-6 weeks to ship.
• Please note the freight company is only responsible for getting the aquarium to the destination address and off-loading it. They are not responsible for carrying it inside.
• All freight charges have been greatly subsidized to help you get up and running with your new Red Sea system.