Best Protein Skimmer


No reef aquarium is complete without a protein skimmer. It’s one of the most important components of the water filtration system. No matter if you have a nano-reef or a 1,000-gallon monster tank, there’s a protein skimmer for every size reef aquarium.

We’ve created this protein skimmer review to make it easy to select the right skimmer for your reef aquarium. Maybe you’re new to the reef hobby and not sure what a protein skimmer is used for. Let’s take a look at what a protein skimmer does and why you need one.

Protein Skimmer Function

Organic pollution in reef aquariums

The worlds coral reefs are continuously flushed with millions of gallons of clean seawater. Unlike the ocean, a reef aquarium is a closed aquatic environment. That means there are no tides and waves to carry away and dilute waste materials. All aquatic life, including fish and corals, release dissolved organic compounds (DOC) into the water. “Organic” means undecomposed, complex compounds. For example, corals periodically shed their mucus coating. Billions of bacteria living in the aquarium release sticky organic substances that “glue” bacteria colonies to live rock. Fish and invertebrate waste, leaky algae cells, fish slime, carbohydrates, proteins and other complex organics are released into seawater.

All of these natural wastes get recycled or flushed away by ocean tides. But unlike the ocean, these dissolved organics accumulate in aquarium water. They’ll cause a yellow tint to the water, absorbing valuable light energy needed by corals. A build-up of organics in a dirty aquarium stimulates harmful pathogenic organisms that cause fish health problems. Organics will eventually decompose, causing elevated nitrate and algae-promoting phosphate in the water. A protein skimmer removes these organics before they can build up and cause water quality and health issues in the aquarium. Here’s how protein skimmers work.

How does a protein skimmer work?

Protein Skimmer Principle

Protein skimmers work on a process known as foam fractionation. Industrial foam fractionation removes undesirable organic compounds by whipping them into foamy mass and skimming it off the surface of a liquid. Aquarium protein skimmers to do the same thing but on a much smaller scale. Air is injected into a reaction chamber, creating millions of tiny bubbles. The rising bubbles create an organic foam at the top of the skimmer. As the foam becomes more concentrated, it is captured in a collection cup. This “organic soup” is discarded and the skimming process starts again.

Protein skimming can’t remove every type of pollutant from the water. Skimmers can only remove “foamy” substances. Ammonia and nitrate are inorganic substances and don’t form a foam. Organic compounds, like fish slime and proteins, do foam and will be removed by a skimmer. The idea is to remove the organics from the water before they’re broken down into ammonia, nitrate, phosphate and other substances. A protein skimmer will improve water quality, reduce nitrate, inhibit algae growth and keep the water clear and sparkling.

Choosing the best protein skimmer for a reef aquarium

Protein skimmers come in many sizes and designs. There is no “one size fits all” approach when selecting a skimmer for your aquarium. There are four basic types of protein skimmers:

  • Hang on the back (HOB)
  • In-sump
  • External
  • In-tank

HOB-style skimmers are self-contained and easy to use. Just hang in on the back of your reef aquarium and plug it in. In-sump protein skimmers are designed to be submerged underwater, inside the filter sump. No plumbing is required. Just plug in the skimmer and you are good to go!

External protein skimmers sit outside the sump. They’re usually larger, designed to handle big reef aquariums. You may have to plumb the water connections using flexible or ridged tubing. In-tank protein skimmers are designed for smaller nano reef tanks. They drop into all-in-one aquarium filters and attach to the top of the aquarium. These are great when you don’t need a large-capacity protein skimmer. We’ve reviewed eight top protein skimmers, highlighting their best applications and features.

Best Protein Skimmer
1. CPR Bak-Pak 2 Protein Skimmer

CPR Aquatics was one of the first manufacturers to make a hang-on-back protein skimmer. The Bak-Pak 2 is a protein skimmer and biological filter combined into one filter device.

The water pump forces aquarium water into the skimmer chamber. Water flows downward in the chamber while air is injected at the bottom. This counter-current design increases contact time with the air bubbles, making the skimmer very efficient. The water leaves the skimmer and flows through a second compartment containing CPR’s Bio-Bale biological filtration media, before returning to the tank. The Bak-Pak 2 is rated for reef aquariums up to 60 gallons. Set up is simple. Level the skimmer by turning the adjustment screws and plug it in. Dimensions: 7.5” x 3” x 17”.


  • High-quality construction
  • Very reliable
  • Plug and play simplicity
  • Counter-current flow increases efficiency


  • The air injection system is a little nosier than other brands

Best protein skimmer
Coralife Super Skimmer

The Coralife Super Skimmer protein skimmer that can hung on the aquarium or used in a sump. Three sizes are available for 65, 125-and 220 gallon aquariums.

Coralife Super Skimmers have a patented needle-wheel water pump with a venturi that mixes the air bubbles into the water. The venturi injects micro-bubbles that rise in the skimmer, forcing dissolved organics into the collection cup.

The Super Skimmer features angled dual injection ports that increase contact time inside the reaction chamber. Water height and foam production is adjustable with a simple turn of the water-level dial. The bubble diffuser plate prevents micro-bubbles inside the skimmer and not the aquarium. The collection cup pops off for cleaning. Models 125 and 220 have a built-in drain option on the collection cup. The skimmer includes everything you need to get it set up quickly. Dimensions: 4.2” x 5.5” x 20.8”.


  • Inexpensive
  • Versatile HOB or in-sump installation


  • Poor set-up and use instructions
  • The skimmer requires adjusting every time it is restarted after a power failure
  • Bulky design takes up more room than other brands

3. Eshopps Nano Protein Skimmer

Small reef aquariums don’t have room for a big protein skimmer. This skimmer is designed to fit inside the filter of most all-in-one style aquariums. It can also be placed inside the tank or in even the filter sump.

The Eshopps Nano Protein Skimmer has a compact footprint measuring 2.25″ x 4.5″ and 11.5″ tall. The Eshopps skimmer uses an adjustable magnetic mount for easily positioning.

The skimmer is made of high-quality acrylic. It comes with an Italian-made Sicce pump. Tiny air bubbles are created with the integrated venturi. The water pumps needle-wheel impeller blends the air bubbles into the water and sends in into the skimmer. The foam is collected in a removable cup for easy cleaning. The Eshopps Nano Skimmer is rated for marine and reef aquariums between 10 and 35 gallons. Dimensions: 5” x 2” x 4”.


  • Small size fits in tight spaces
  • Very effective skimmer
  • Easy to clean skimmate cup


  • Collection cup does not have a drain

Reef Octopus protein skimmer
4. Reef Octopus Classic 100-HOB Protein Skimmer

The Reef Octopus Classic is a hang-on-back one of the best protein skimmer rated for reef aquariums up to 105 gallons.

The skimmer features high-quality cast acrylic body construction, easy disassembly for maintenance and includes an “air shredding” Aquatrance 1000 water pump. The needle-wheel impeller injects the air bubbles into the skimmer’s water stream, sending it into the contact chamber. Foam is collected in the skimmer cup. The cup can never overflow. It is designed to allow overflow back into the aquarium. This is a great feature when you are away from home and can’t service the skimmer.


  • Very effective protein skimmer
  • Skimmer cup can’t overflow
  • Works on larger aquariums without a sump
  • Micro-bubbles don’t pour back into the aquarium


  • The set-up manual is very basic

Bubble Magus Protein Skimmer
Bubble Magus Curve 7 Protein

The Bubble Magus Curve 7 skimmer is designed for use inside a filter sump. A sump is an ideal out of the way location for a larger protein skimmer. The Bubble Magnus curved body design allows for a smooth transition of the foam to move up into the collection cup. The needle wheel pump makes the right-sized bubbles to create dry foam.

The Curve 7 has special bubble plate feature that reduces turbulence inside the skimmer, which increases skimming efficiency. The collection cup is easily removed for cleaning. All of the Bubble-Magus skimmers run silently. The Bubble Magus Curve 7, handles reef tanks up to 240 gallons. Dimensions: 9.25” x 7.87” x 20.8”.


  • Excellent build-quality
  • Water pump sits inside the skimmer
  • Wine-shaped body to decrease turbulence when bubbles rise
  • Quiet operation
  • Easy to assemble and clean


  • None

NYOS Quantum Protein Skimmer
6. NYOS Quantum 220 Protein Skimmer

A large reef aquarium requires a big protein skimmer. The Quantum 220 fits inside your filter sump. Rated for tanks up to 500 gallons, The NYOS Quantum 220 runs silently while stripping the water of organic pollutants.

The water pump is positioned inside the skimmer to save space. NYOS has developed a high-efficiency impeller called the Hybrid Wheel. The impeller has a lattice-shaped base, on which numerous very narrow needles are mounted. This design ensures that countless extremely fine micro air bubbles are generated. Reduced weight coupled with high precision manufacturing results in lower maintenance and at the same time low energy consumption. Water quantity and air flow can be set separately and independently. Dimensions: 9.25” x 12.3” x 23.82”.


  • Optimum air-water mixture for maximum performance
  • Very quiet operation
  • High performance,
  • low power consumption
  • Easy-to-use settings


  • None

Reef Octopus protein skimmer
Reef Octopus Super SRO-3000EXT

The Ref Octopus Super SRO-3000EXT protein skimmer is an external skimmer for large reef aquariums. The 3000EXT is rated for reef aquariums up to 250 gallons.

This big skimmer features a refined hybrid cone design that stabilizes foam production. Reduced turbulence in the neck area allows for more time for the organics to rise and collect in the cup. The Super SRO uses a matched external Bubble Blaster water pump with a pinwheel impeller. You’ll need to plumb and install a separate water feed pump (500 GPH) to run the protein skimmer. Dimensions: 16”x 13.5” x 26”


  • 2-year warranty on the pump
  • Skimmer cup is easy to clean
  • Very effective skimmer
  • Easy to adjust operation


  • Requires extra plumbing work and external water pump

hydor slim skim nano protein skimmer
8. Hydor SlimSkim Nano Protein Skimmer

Nano and small reef aquariums need a small skimmer that is efficient but not too large. The SlimSkim is designed to work with most smaller reef tanks.

The SlimSkim Nano is an internal skimmer engineered for small tanks. The unique overflow intake design pulls water from the surface, removing oily bio-slicks from the surface. Once inside the skimmer, the energy-efficient (4 watts) venturi air pump injects millions of micro-bubbles. The bubbles rise to the surface, concentrating organic waste as a dry foam. Adjust the skimmer by raising or lowering the collection cup. The easy to remove collection cup makes maintaining the skimmer easy. The magnetic attachment systems let you install the skimmer just about anywhere.

This nano skimmer is rated for 23 to 35 gallons. Dimensions: 3 1/8” x 3 1/8″ x 12” * *Height size = skimmer body only (without collection cup).


  • Quiet operation
  • Easy to maintain
  • Effective protein skimmer for nano and cube tanks.
  • Needs almost not adjusting


  • None

Final thoughts

There are many brands and styles of protein skimmers to choose from. Our list contains proven top performers with a history of reliable operation. So how to choose which one is right for you? Here’s the top things to consider when shopping for a protein skimmer.

  • Is it rated for my aquarium? It’s always safe to oversize the skimmer. An under-sized protein skimmer may not be able to keep up with the waster accumulation in the aquarium.
  • Where will it be installed? If you’ve got a nano reef, you’ll probably want to place the skimmer in the filter, or maybe inside the aquarium. Maybe an in-sump design is best for your tank. Be sure to measure the height inside the stand. Make sure there is room to remove the skimmer cup! If going for a HOB skimmer, make sure you’ve got enough room behind the aquarium.
  • Will the skimmer fit inside my sump? Measure the footprint of the protein skimmer and see if it will fit inside your sump. Some skimmers have the water pump inside the skimmer body to save space.

The good news is that all of these protein skimmers work great when matched to the right aquarium. Take a look at the specs and features and see which models will work best in your reef aquarium. Even though we rate all of the protein skimmers highly, you may find most of the set-up guides included in the box lacking detail. We recommend searching YouTube for user tips on setting the skimmer up and dialing in the settings.