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Red Sea Protein Skimmer RSK-900


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Item #: RS1290

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Red Sea Reefer RSK Protein Skimmers - Efficient - Quiet - Ergonomic

Red Sea Reefer Skimmers are powered by Sicce`s PSK Skimmer Pumps, a pump well known among hobbyists around the world for their efficient output.

The silent operation of the Reef Skimmers are attributed to the large air intake silencer, and the vibration dampening feet and connections.

The diffusion chamber of the Reefer Skimmers disperses microbubbles produced by the PSK skimmer pump evenly through the conical ergonomic body, while maintaining air and water flow.


  • FoamView window for foam regulation
  • Neck cleaner integration
  • Drain port connection with 3 foot draining hose
  • Graduated collection cup to monitor skimmate production
  • Highly effective air silencer
  • High volume reaction chamber
  • Sicce PSK Skimmer pump
  • Two positioning options for the skimmer pump
  • Precise gate valve for skimming control
  • Vibration reducing footing

RSK Ratings





SPS Tanks: 80 Gallons / 300 Liters 160 Gallons / 600 Liters 240 Gallons / 900 Liters
Mixed Reef Tanks: 160 Gallons / 600 Liters 320 Gallons / 1200 Liters 500 Gallons / 1800 Liters
Fish Only Tanks: 240 Gallons / 900 Liters 500 Gallons / 1800 Liters 740 Gallons / 2700 Liters


Sicce Pump Model: PSK-600 PSK-1000 PSK-1200
Air Flow (GPH/LPH): 130 / 500 195 / 750 235 / 900
Water Flow (GPH/LPH): 265 / 1000 400 / 1500 530 / 2000
Dimensions: 9.1L x 8.3"W x 21"H 10.2"L x 9.4"W x 22"H 11.4"L x 10.6"W x 23"H
Recommended Water Depth: 6-8" / 16-20cm 7-8" / 18-20cm 8-9" / 20-24cm

Compatibility Chart





Reefer Nano
Reefer 170
Reefer 250 V1
Reefer 250 V3 **
Reefer 350 V1 * *
Reefer 350 V3
Reefer XL 425 V1 * * *
Reefer XL 425 V3
Reefer 450 * *
Reefer XL 525 V1 * * *
Reefer XL 525 V3
Reefer XXL 625
Reefer XXL 750
Reefer Peninsula 500
Reefer Peninsula 650
Max E-170
Max E-260
Max S-400
Max S-500
Max S-650 ***
*Skimmer may need to be raised, **Refugium wall will need to be removed, ***Place in reactor chamber

Manufacturer information

With a dedicated team of scientists and other professionals, Red Sea is widely recognized as a leading innovator and manufacturer of quality products for aquarium hobbyists. Red Sea constantly strives to provide hobbyists of all levels with highly effective solution-driven products designed to make your fish-keeping experience as enjoyable and successful as possible.

The embodiment of Red Sea’s dedication to providing solutions for today’s reef-keepers is its range of MAX-NANO, MAX-E & MAX-S aquariums- The only choice for true Plug & Play™ coral reef aquariums, now featuring the very latest in LED lighting technology.

For advanced reef-keepers the Red Sea REEFER provides a great platform into which you can add your own selection of hardware. With its ultra-clear glass, ATO built-in, silent flow valve and superb quality of finish the REEFER sets the standard for those wishing to customize. REEFER is also available as a Deluxe version with LED lighting included.

Red Sea’s unique Reef Care Program (RCP) provides a comprehensive, safe and easy to use program for testing and supplementing within reef aquaria, and is perfectly complemented by Red Sea’s Coral Pro & Red Sea Salt’s, which has become the salt of choice for those seeking the very highest quality water quality for their coral reef aquariums. Both salts are made using a unique natural process which delivers unrivalled homogeneity and is perfect for delicate corals. Check your individual bucket of salt’s composition using Red Sea’s innovative new “MyBatch” software.

Whatever your aquatic needs, Red Sea delivers high quality innovative, solution based products.

4 Stars


Reviewed on
November 22, 2020

Yes, I would recommend this.

Red Sea Skimmer

Pros: Solid skimmer, great features, solid performance reviews, great price compared to other comparable skimmers.

Cons: The snug fitting rubber gasket skimmer cup design clearly can cause users like "NMILLER" to crack their skimmer.

The reviewer by the name of "NMILLER" should provide more detail and pics to problems with this skimmer...especially how your collection cup became "stuck" to the body with routine cleaning as the user stated. It's a rubber gasket around the base of the skimmer cup...how would that 'weld' stuck after only a year and a half worth of use??? I have the RSK 300 and the build quality meets or exceeds the quality of skimmers available in it's class....and I've seen and held many skimmers. When they were introduced, I talked to local LFS's that were running these, along with other brand skimmers, in their display tanks. And they were satisified with the performance...which is why I made the purchase. And I'm upgrading to a 300 gallon tank and will be buying the RSK 900 during Black Friday. Had to write this because I hate bs reviews on products.

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Reviewed on
October 05, 2020

No, I would not recommend this.

Not good

I will say that this skimmer when working effectively produces a very good waste. However when the unit is not working properly it will overfill and splash water everywhere. Second off the build quality is very cheap. After a year and a half the collection cup got stuck to the body and I keep my tank equipment very clean. While trying to disconnect the collection cup the plastic connection between the body and cup cracked. This make the skimmer pretty much useless. This product has nice features but was a truly a waste of money.

Was this review helpful? 0 3

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