Red Sea RSK 900 — REEFER Skimmer Sicce PSK-1200 Mixed Reef 500 gal - Red Sea

The Red Sea RSK 900 REEFER Skimmer protein skimmer is the most powerful model in the REEFER Skimmer range, designed for large reef aquariums up to 900 liters (240 gallons) in heavy SPS load and up to 1,800 liters (500 gallons) in mixed reef. Equipped with the Sicce PSK-1200 needlewheel pump with oversized venturi, it produces an impressive air volume of 900 L/h and a water flow of 2,000 L/h through a high-performance reaction chamber that maintains an ORP (REDOX) level above 350 mV — a level normally associated with ozone treatment, without ozone.

Video — Red Sea REEFER Skimmer

Capacity based on biological load

The "900" in RSK 900 refers to the capacity in liters for a heavy-load SPS aquarium. Actual capacity varies depending on your reef type:

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

RSK 900 — Who is it for?

The RSK 900 is the choice for reefers managing large systems: REEFER 625, REEFER 750, REEFER Peninsula 650/700, or custom sumps of 200 gallons and more. With its Sicce PSK-1200 pump that pushes 900 liters of air and 2,000 liters of water per hour through the largest reaction chamber in the range, the RSK 900 processes a significantly larger volume of water than the RSK 600. If your aquarium exceeds 160 gallons under SPS load or 320 gallons in a mixed reef, this is the model for you.

RSK Range Comparison

• RSK 300: PSK-600 Pump | Air 500 L/h | Water 1,000 L/h | SPS 80 gal | Mixed 160 gal
• RSK 600: PSK-1000 Pump | Air 700 L/h | Water 1,500 L/h | SPS 160 gal | Mixed 320 gal
• RSK 900: PSK-1200 Pump | Air 900 L/h | Water 2,000 L/h | SPS 240 gal | Mixed 500 gal

Features and Functionality

Noise Reduction — Concrete Efforts

Red Sea has integrated several elements to reduce operating noise: an oversized air inlet silencer on the venturi intake, anti-vibration rubber feet, and vibration-absorbing connectors between each component. As the most powerful skimmer in the range, with the PSK-1200 pump drawing 900 L/h of air, the RSK 900 will be noisier than the 300 and 600 models. For reefers who want to go further in silence, upgrading to the DC pump (sold separately) offers significantly smoother operation.

FoamView Window and Integrated Neck Cleaner

The collection cup incorporates the FoamView window to see the foam rise in the neck without removing the cup, and an integrated neck cleaner in the lid — a rotating bar with a double-sided thick rubber squeegee that removes buildup on the neck walls with a few rotations. With the drain port and its 1-meter hose with valve, you can empty the cup into an external container without ever removing it.

Hydrodynamic Diffusion Chamber

The diffusion plate at the bottom of the reaction chamber has numerous and prominent outlet holes that uniformly disperse the fine bubbles created by the PSK pump throughout the cone. This design does not reduce either air flow or water flow, maximizing air-water contact time for optimal extraction of organic waste and proteins.

Assembly and Maintenance Designed for Reefers

Red Sea uses custom short-thread nylon screws — just a few turns to screw them in, and the wide thread prevents salt particles from getting stuck. The Sicce PSK-1200 pump can be removed with a click thanks to the click-in/out support for quick cleaning. The cup locks into the neck with a waterproof snap compression. The pump's cable routing is neatly channeled into the support without dragging in the sump water.

3 Orientation Options

The conical body's symmetrical base can be installed in 3 different orientations to position the pump's water intake and the skimmate regulator wherever you want in your sump. Whether your sump is narrow with left, right, or front access, there is an optimal configuration.

Designed for the Red Sea REEFER Ecosystem

The RSK 900 integrates perfectly into the skimmer chamber of Red Sea REEFER systems. The water level indicator on the skimmate regulator matches the exact water level inside the REEFER sump — everything is calibrated to work together. Compatible with REEFER 525, REEFER 625, REEFER 750, REEFER Peninsula 650, and REEFER Peninsula 700 (G1, G2, and G2+) models. Also works in any third-party sump with a water height of 20 to 23 cm (8 to 9 inches).

Technical Specifications

• Model: RSK-900
• Pump: Sicce PSK-1200 Needlewheel (AC)
• 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 23 cm (8 to 9 in)
• Skimmate Regulator: Notched precision valve controlling water level in the reaction chamber
• Materials: Transparent acrylic, saltwater resistant components

Box Contents

• 1 x RSK 900 skimmer body with conical reaction chamber
• 1 x Sicce PSK-1200 pump with click-in/out support
• 1 x Collection cup with FoamView window and integrated neck cleaner
• 1 x Oversized air inlet silencer with supply hose
• 1 x 1-meter drain hose with valve
• Assembly base with 3 orientation options
• Short-thread nylon screws and hardware
• User manual

DC Upgrade Available

The RSK 900 can be upgraded with the Red Sea REEFER DC Skimmer pump, which replaces the original Sicce PSK-1200 AC pump. The DC pump offers significantly smoother operation, reduced power consumption (30W), an air flow of 900 L/h with variable flow controlled via the ReefBeat app, and Self-Leveling functionality that automatically adjusts skimming intensity to prevent foam overflow. The ReefRun Dual controller is required (sold separately).

Why Choose from ReefSolution

Authorized Red Sea retailer in Canada with technical support in French. Complementary products available: Red Sea REEFER DC Skimmer Pump — DC upgrade pump with ReefBeat control and Self-Leveling, Red Sea RSK 600 REEFER Skimmer — Intermediate model for smaller systems, Red Sea ReefMat 1200 — Automated mechanical filtration for large sumps, Red Sea Coral Pro Salt — Reef salt formulated for REEFER systems. Shipping across Canada.

Frequently Asked Questions

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

Yes. The RSK 900 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 offers the ideal capacity. It is also the recommended model for the REEFER 625 and REEFER Peninsula 650/700.

Will the RSK 900 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 chosen orientation from the 3 assembly options. It is the largest skimmer in the RSK range — measure your skimmer chamber and choose the appropriate orientation. The recommended water height is 20 to 23 cm (8 to 9 inches), deeper than the RSK 300 and 600.

How do I adjust the RSK 900 skimmer?

The Sicce PSK-1200 AC pump operates at a fixed speed. Skimming adjustment is done via the notched precision valve that controls the water level inside the reaction chamber. By raising the water level, the foam is pushed higher into the neck for wetter skimming. By lowering the level, the foam rises less for drier skimming. During break-in (first 1-2 weeks), set the valve for a lower water level to allow the skimmer to stabilize. After break-in, gradually raise the level to obtain dense, stable foam in the neck. Use the FoamView window to monitor without touching the cup.

Can I upgrade the AC pump to the DC pump later?

Yes. The Red Sea REEFER DC Skimmer pump is a direct replacement for the PSK-1200 AC pump. It is the same universal DC pump for all three RSK models — it connects to the ReefRun Dual controller (sold separately) and offers variable flow, an automatic Self-Leveling function, and integration with the ReefBeat app for remote control.