Red Sea REEFER S-850 G3 – Premium All-in-One Reef Aquarium System

179.6 Gallon Eurobraced Glass Display
Glass Sump Compatible with ReefMat and REEFER DC Skimmers
Ready-to-Use Plumbing w/ New ReefGate Flow Valve
ReefATO+ Auto Top Off System & Slide-Out Control Panel Included
Choice of Black or White Aluminum-Framed Stand

Red Sea has been building aquariums for years, delivering high-quality, thoughtfully engineered systems that make reefing easier and more enjoyable. The REEFER G3 series is a top choice for hobbyists who want a premium aquarium with the flexibility to choose their own filtration, lighting, and equipment. Each system offers a strong, reef-ready foundation with smart features and a clean, modern design.

The REEFER S-850 G3 Aquarium

Red Sea's S-Series lineup includes all the features of the standard REEFER G3 aquariums, but with deeper and wider dimensions. All S-Series aquariums also come with eurobracing at the top of the tank for added structural support and peace of mind. The low-profile overflow box has dual side-facing return outlets that can be attached to a single or dual return pump setup.

Display Tank Dimensions: 180L x 65H x 68W cm

Aluminum Marine-Spec Cabinet

REEFER S-Series tanks start with a robust aluminum structure. The Marine-Spec cabinetry attaches directly to the aluminum structure, giving you both form and function. The adjustable feet allow for perfect leveling on just about any surface, and are hidden by the cabinet exterior for a more elegant look. Stands are available in black or white finishes to complement any space.

Reef-Ready Sump

The main sump is refugium-ready and has an adjustable height skimmer chamber, enabling you to set the water level between 20-28cm (7.9"-11") for optimal skimmer performance. S-850 and S-1000 models also include an extension sump that can be used as a dedicated frag tank, larger refugium, or for extra filtration equipment. Alternatively, the extension sump can be disconnected from the main sump and used as an auto top off reservoir.

The included sump is compatible with a wide range of filtration equipment, including Red Sea’s ReefMat fleece roller filters and REEFER DC protein skimmers, giving you plenty of upgrade options as your system grows (ReefMat and REEFER Protein Skimmer are sold separately).

Recommended Sizes:

ReefMat 1200 Fleece Rol l er Filter
REEFER DC 900 Protein Skimmer

Ready-to-Use Plumbing

REEFER G3 systems include all the plumbing you need, ready for quick assembly with no gluing required. The redesigned G3 layout reduces the number of 90-degree turns for smoother flow, while the new ReefGate flow valve makes it easy to fine-tune your system's drain plumbing so that it runs quietly. REEFER S-850 and S-1000 G3 models have been upgraded to 32mm return pipes instead of the 25mm used in the previous generation.

ReefATO+ Auto Top Off System

Each REEFER G3 system includes the ReefATO+, combining top off control, temperature monitoring, and leak detection all in one device connected to the ReefBeat App.

Automatic Top Off: The ReefATO+ sensor features a built-in backup sensor 1" above the primary sensors to automatically shut down the ATO pump in the event of an overfill. With multiple probes built onto the sensor, an indication of actual water level can always be seen on the ReefBeat App.
Temperature Monitoring: The temperature sensor integrated in the ATO+ sensor has been pre-calibrated to give an accuracy of ±0.1°. If the temperature goes outside the acceptable range, you will be sent a ReefBeat notification.
Leak Detection: The highly sensitive, Reef-Spec leak detector (with saltwater resistant titanium probes) detects both saltwater and RO/DI water. If a leak is detected, the ATO pump is immediately disabled, and after a few seconds to confirm that the leak persists, the controller sounds an optional audible alarm and sends a notification.

Slide-Out Control Panel 60

The REEFER S-Series features a built-in slide-out control panel designed to keep your aquarium electronics organized and accessible. Crafted from marine-spec laminated plywood and stainless steel, this durable panel offers a clean, professional mounting solution for your reef monitoring and maintenance equipment

Component	Specification/Details
Display Tank Dimensions	180L x 65H x 68W cm
Display tank Volume	680 L
Total System Height	153 CM
Total System Volume	850 L
Sump Volume	170 L
Front Glass Thickness	19 MM
Side Glass Thickness	19 MM
Bottom Glass Thickness	19 MM
ATO Pump Power	6-10W
Rim Type	EURO BRACE + BOTTOM BRACE
Reef ATO+ & Slide Out Control Panel 60	INCLUDED

What's Included?

REEFER S-850 G3 Aquarium
Aluminum Marine-Spec Cabinet (in your selected color)
Glass Sump & Pre-Glued Plumbing
ReefATO+ Auto Top Off System
Slide-Out Control Panel 60

5 Year Manufacturer Warranty (3 years standard + 2 upon registration)

All REEFER G3 aquariums include a standard 3-year warranty. Register your brand-new Red Sea system within 90 days of the original date of purchase to add 2 years of protection at no extra cost. Please see Red Sea's website for full terms & conditions.

Red Sea REEFER S-850 G3 - Advanced Reef System (223 Gallon | 850 Liters)

Available Options

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