Red Sea RSK 900 DC — REEFER Self-Leveling DC Pump Protein Skimmer ReefBeat 240 gal SPS - Red Sea

The Red Sea RSK 900 DC REEFER Skimmer is the most powerful smart skimmer in the Red Sea range, featuring patented Self-Leveling technology that eliminates foam overflows and continuously self-regulates. Equipped with a variable flow Sicce PSK DC-1200 pump pushing 900 L/h of air and 2,000 L/h of water, a dual-action Skim Sensor, and full integration with the ReefBeat ecosystem, this is the DC skimmer for large reef aquariums up to 900 liters (240 gallons) with heavy SPS loads and up to 1,800 liters (500 gallons) for mixed reefs.

Important: The Red Sea ReefRun Dual Controller is required to operate this skimmer and is not included. The ReefRun Dual Controller is sold separately and can simultaneously control the DC skimmer AND a ReefRun DC return pump — one controller for two devices.

No More Overflows — A Game Changer for Reef Keepers

Any reef keeper who has owned a protein skimmer knows the same frustration: you leave for work or go to bed, and when you return, the cup has overflowed into your sump or, worse, onto your floor. Someone fed the fish, salinity shifted, a water change disturbed the skimming, or simply the water chemistry fluctuated. With a classic AC skimmer, you're constantly monitoring the neck, adjusting the valve, worrying from afar. The larger the skimmer, the more amplified the problem — an overflow on an RSK 900 causes much more damage than an RSK 300.

The RSK 900 DC changes the game. Self-Leveling technology monitors the foam wetness in the neck in real-time with a dual-action solid-state sensor. As soon as the foam becomes too wet or rises too quickly, the DC pump automatically reduces its intensity — just enough to prevent overflow. Then it gradually increases, little by little, depending on the foam wetness, until it reaches your programmed intensity and restores stable skimming. This is not a simple float switch that shuts everything off: your skimmer continues to aerate and circulate water continuously, even in reduced Self-Leveling mode. The technology is patented (patent pending) by Red Sea — no other skimmer on the market does this.

At ReefSolution, we use DC skimmers on our own systems and we love them. The peace of mind knowing the skimmer won't overflow overnight or when we're at the shop is priceless. It's the best investment we've made in our reef systems.

Videos — Red Sea REEFER DC Skimmer

Capacity by Biological Load

• SPS / Heavy Load: Up to 900 L (240 gal) — Acropora, Montipora, frequent feeding
• Mixed Reef / Medium Load: Up to 1,800 L (500 gal) — Mixed SPS, LPS, soft corals
• Fish Only / Light Load: Up to 2,700 L (740 gal) — Fish-only aquarium with few corals

RSK 900 DC — Who is it for?

The RSK 900 DC is the choice for reef keepers managing large systems: REEFER 625, REEFER 750, REEFER 900, REEFER Peninsula 650/700, REEFER S-850/S-1000, or custom sumps of 200 gallons and up. If your aquarium exceeds 160 gallons with a heavy SPS load or 320 gallons for a mixed reef, or if you have a heavily fed system with demanding SPS corals, the RSK 900 DC is the model for you — with the added security of Self-Leveling on a skimmer of this power.

How Self-Leveling Works

The Skim Sensor installed in the collection cup lid continuously monitors two parameters:

• Foam Wetness: Detects when the foam in the neck becomes too wet — a sign that an overflow is approaching
• Waste Level: Monitors the filling of the collection cup and sends you a notification when it's time to empty it

When the wetness exceeds the threshold you've configured in the ReefBeat app, the DC pump immediately reduces its intensity. Then it gradually adjusts its power — not on/off, but continuous regulation — until stable skimming is restored. This cycle repeats automatically, 24/7, whether you are in front of your aquarium or halfway around the world.

ReefBeat Integration — Your Skimmer in Your Pocket

Connected to the ReefRun Dual Controller, the RSK 900 DC integrates with the Red Sea ReefBeat app for total control:

• Remote Control: Adjust pump intensity and Self-Leveling threshold from your phone, anywhere
• Notifications: Alerts when the cup is full, when the pump is blocked, or running dry
• Feed Mode: Custom feeding scenario — skimmer reduces or shuts off during feeding, then restarts automatically after your configured delay
• Maintenance Mode: Ordered restart sequence after maintenance — return pump restarts first, then skimmer, then wavemakers, then dosers, in the order and timing you choose
• Emergency Mode: Quick actions in case of emergency
• Schedule Programming: Activate and deactivate skimming according to a custom daily schedule

Skimmer Features

• Sicce PSK DC-1200 Pump: Variable flow DC needlewheel pump, manufactured by Sicce for proven reliability
• Skim Sensor: Dual-action solid-state sensor in the collection cup lid for Self-Leveling regulation and notifications
• Hydrodynamic Diffusion Chamber: Diffusion plate with prominent holes that uniformly disperse fine bubbles through the cone without reducing air or water flow
• FoamView Window: Viewing window integrated into the collection cup to monitor foam without removing the lid
• Integrated Neck Cleaner: Rotating bar with thick double-sided rubber squeegee to remove buildup on the neck walls
• Skim Regulator: Precision notched valve controlling the water level in the reaction chamber
• Drain Port: 1-meter hose with valve for connection to an external waste collector
• 3 Orientation Options: Symmetrical base installable in 3 positions to adapt the water inlet and regulator to your sump
• Noise Reduction: Anti-vibration feet, rubber connectors, oversized air intake silencer. The variable flow DC pump produces less vibration than fixed-speed AC pumps. As the RSK 900 DC is the most powerful in the range with 900 L/h of air, the noise level will be higher than the 300 and 600 DC models. The noise level still depends on your setup.

Technical Specifications

• Model: RSK 900 DC
• Pump: Sicce PSK DC-1200 needlewheel (DC, variable flow)
• Power Consumption: 30W
• Air Flow: 900 L/h (235 GPH)
• Water Flow: 2,000 L/h (530 GPH)
• Maintained ORP: 350+ mV
• Height: 59 cm (23 in)
• Footprint: 29 x 27 cm (11.4 x 10.6 in) or 32 x 24 cm (12.6 x 9.4 in) depending on orientation
• Recommended Water Height: 20 to 24 cm (8 to 9 in)
• Sensor: Dual-action solid-state Skim Sensor
• Connectivity: ReefBeat via ReefRun Dual Controller (required, sold separately)

DC Range Comparison

• RSK 300 DC: Air 500 L/h | Water 1,000 L/h | 20W | SPS 80 gal | Mixed 160 gal
• RSK 600 DC: Air 750 L/h | Water 1,500 L/h | 25W | SPS 160 gal | Mixed 320 gal
• RSK 900 DC: Air 900 L/h | Water 2,000 L/h | 30W | SPS 240 gal | Mixed 500 gal

REEFER Compatibility

The RSK 900 DC is designed to fit into the skimming chamber of Red Sea REEFER systems. Compatible with REEFER 525, REEFER 625, REEFER 750, REEFER 900, REEFER Peninsula 650/700, REEFER S-850, and REEFER S-1000 models (G1, G2, G2+, and G3). Some models may require adjustment. Also works in any third-party sump with a water height of 20 to 24 cm.

Box Contents

• 1 x RSK 900 DC skimmer body with conical reaction chamber
• 1 x Sicce PSK DC-1200 pump with click-in/out mount
• 1 x Collection cup with FoamView window, integrated neck cleaner, and lid with Skim Sensor housing
• 1 x Dual-action Skim Sensor
• 1 x Oversized air intake silencer with supply hose
• 1 x 1-meter drain hose with valve
• 1 x Controller cable
• 1 x Universal power supply + AC cable
• Assembly base with 3 orientation options
• Short threaded nylon screws and hardware
• User manual

Not included: The Red Sea ReefRun Dual Controller is required to operate the DC pump and Skim Sensor. It is sold separately and can also control a ReefRun DC return pump simultaneously.

RSK 900 DC vs RSK 900 AC — Why Choose DC?

• Automatic Self-Leveling: The AC has no overflow regulation. The DC continuously monitors foam and self-regulates. On a skimmer of this power, overflow protection is even more critical.
• Variable Flow: The AC operates at a fixed speed. The DC adjusts its power in real-time.
• ReefBeat Connectivity: Remote control, notifications, scheduling, automated modes — impossible with the AC.
• Smoother Operation: The DC pump produces less vibration than the AC Sicce PSK-1200 pump.
• Reduced Power Consumption: 30W for the DC.
• Continuous Aeration: Even in reduced Self-Leveling mode, the pump continues to circulate and aerate the water. A float switch shuts everything off.

Why Choose ReefSolution

Authorized Red Sea dealer in Canada with technical support in French. We use DC skimmers on our own systems at ReefSolution — we can guide you through installation and ReefBeat configuration. Complementary products: Red Sea ReefRun Dual Controller — Required controller for the DC skimmer, Red Sea RSK 600 DC REEFER Skimmer — Intermediate model for smaller systems, Red Sea ReefRun DC Pump — DC return pump controllable via the same controller, Red Sea Coral Pro Salt — Reef salt formulated for REEFER systems. Shipping across Canada.

Frequently Asked Questions

Does the RSK 900 DC work without the ReefRun Dual Controller?

No. The ReefRun Dual Controller is required to power and control the PSK DC-1200 pump and Skim Sensor. It is not included with the skimmer and must be purchased separately. The advantage is that a single controller can manage both the DC skimmer and a ReefRun DC return pump simultaneously — one purchase for two devices.

Does Self-Leveling really work? No more overflows?

Yes. This is not a simple float switch that turns off the skimmer when the cup is full. The solid-state sensor continuously monitors foam wetness in the neck and adjusts the pump's power in real-time — gradually, not on/off. After feeding, a water change, or a salinity fluctuation, the pump reduces just enough to stabilize the foam, then gradually increases. At ReefSolution, we use this technology on our own systems and the results are remarkable — no more panicking to check the skimmer.

Is the RSK 900 DC the right choice for my REEFER 750 or a 200+ gallon aquarium?

Yes. The RSK 900 DC is recommended by Red Sea for mixed reefs up to 500 gallons and SPS aquariums up to 240 gallons. For a REEFER 750 (200 gallons) with a heavy SPS load, the RSK 900 DC offers ideal capacity with the security of Self-Leveling. It is also the recommended model for the REEFER 625, REEFER 900, and REEFER Peninsula 650/700.

How do I adjust the RSK 900 DC skimmer?

Two levels of adjustment. Physical adjustment is done via the precision notched valve that controls the water level in the reaction chamber — raise the level for wetter skimming, lower for drier skimming. Smart adjustment is done via the ReefBeat app where you configure the DC pump intensity and the Self-Leveling sensitivity threshold. The combination of both gives you total control over the quality and quantity of foam produced.

Will the RSK 900 DC fit in my sump?

The footprint is 29 x 27 cm (11.4 x 10.6 in) or 32 x 24 cm (12.6 x 9.4 in) depending on the orientation chosen from the 3 assembly options. This is the largest skimmer in the range — measure your skimming chamber and water height (20-24 cm recommended, deeper than the 300 and 600 DC). In REEFER 625+ and 750+ sumps, the RSK 900 DC is designed to integrate perfectly.