Best 9 Hang-on Back (HOB) Protein Skimmers for Aquarium

Saltwater aquariums are built differently. Thanks to a higher bioload and the absence of faster toxin disintegration, you need additional equipment that eliminates poop, leftover food, and unwanted organisms. 

Protein skimmer

Enter protein skimmers. Typically manufactured in a cylindrical shape, these devices use a submersible pump to create air bubbles that bring the waste materials to the top collection cup through sheer surface tension. 

While they all clean your tank, protein skimmers aren’t a replacement for bio-mechanical filters or bio-pellet reactors. Although skimmers eliminate a large amount of organic debris and help them carry out the operation of maintaining the water parameters, none of them alone can maintain saltwater quality. 

In this article, we will review a few of my favorite protein skimmers to help you choose the best one. 

Best 9 Hang-on Back Protein Skimmers for Aquarium

1. OCTO BH-2000 Protein Skimmer

OCTO BH-2000 Protein Skimmer    

Sufficient for 100-175 gallon saltwater tanks, the OCTO BH-2000 is the aquarist choice of HOB skimmer. Built with premium acrylic and an improved venturi design, this protein skimmer is easy to clean and has a low noise level. It also has a tuning cup and an O-ring to adjust the desired foam height.


  • Powered by Aquatrance 2000s Skimmer Pump

Pumping 198 gallons per hour, the Aquatrance 2000s easily is one of the best pumps for this protein skimmer. Although it lacks flow rate control, it’s powerful enough to neutralize organic debris from larger tanks. 

  • Reduced Heat Transfer to Water

Thanks to the external motor, minimal heat is transferred to the tank—maintaining a stable temperature throughout. 

  • Adjustable Skimmer Attachment

While the pump itself isn’t flow rate adjustable, skimmer adjustment accessories are present in the mechanism to control the height of the foam column. 

  • 1-Year Warranty on Skimmer and Pump

A fully covered 1-year warranty on the skimmer and the pump is offered by Octo for easy returns and repair. 


  • External pump mount.
  • Venturi air injection system. 
  • Robust acrylic construction. 
  • Smaller footprint. 


  • Pricier than most HOB skimmers. 
  • Touch to assemble without instructions.

2. Reef Octopus Classic 152-S Protein Skimmer

Reef Octopus Classic 152-S Protein Skimmer    

Built to cycle up to 200 gallons of light-stocked saltwater fish tanks, the Reef Octopus Classic 152-S delivers a 140 GPH flow rate through its 6” tapered body. Specifically designed for the purpose, the body of this skimmer efficiently stabilizes and concentrates organic-rich foam to the collection cup.  


  • Powerful 1800S Pump

The pinwheel 1800S submersible pump is powerful enough to create and push bubbles through the wine glass shape body to concentrate them in the collection cup. 

  • Super Cone Body

Wider at the bottom and narrower at the top, the super cone body of this protein skimmer prevents turbulence, stabilizes organic matter, and enhances foam formation for effective operation. 

  • 2-Year Warranty

Although quite durable, the acrylic body of the skimmer and the pump are covered under a 2-years warranty. Any mechanical or leakage issues are taken care of without any cost. 

  • Bubble Free Output

Great care is taken by Reef Octopus to ensure that the bubbles produced in the skimmer don’t end again up in the aquarium. 


  • Quiet application. 
  • Solid acrylic construction.
  • Compact footprint.


  • Not truly HOB. You need to source a mounting bracket to use it like one. 
  • The price is in a higher range. 



A flat, perfect hang-on back protein skimmer, the AquaMaxx 1.5 is easy to install and maintain. Employing a modified Italian Sicce pump, this setup is designed to cater to light bioload tanks up to 90 gallons. Requiring 4” of clearance to remove the collection cap, the AquaMaxx has a small footprint of only 7.5 X 3.5 inches.  


  • Upgraded Italian Sicce Needle Wheel Pump

In addition to the Sicce pumps being made for both wet and dry operations, modifications done on them ensures that the skimmer produces the optimum size and amount of bubbles. 

  • Cell-Cast Acrylic Body

Premium cell-cast acrylic is used to construct the AquaMaxx skimmer. The cell-cast acrylics are thermally stable and more resistant to solvents—making the skimmer perfect for saltwater operations. 

  • Simple to Install and Operate

You can easily assemble the AquaMaxx skimmer by referring to the instruction manual available online and watching the video posted by the sellers. 

  • Easy Foam Level Adjustment

The removable collection cup also acts as the foam level adjuster. Just move it vertically to adjust the foam level to wet and dry. 


  • Quiet and efficient operation. 
  • Easy to remove collection cup and cleaning.
  • Great suction power. 


  • Releases micro bubbles in the tank constantly.

4. Simplicity 240DC Protein Skimmer

Simplicity 240DC Protein Skimmer    

Equipped with a speed adjustment controller and DC motor, the Simplicity 240DC is designed to skim saltwater tanks up to 240 gallons. Its small footprint and relatively quiet operation make it one of the most popular protein skimmers. The unit also is pretty easy to install and disassemble, thanks to a thumbscrew assembly. 


  • Adjustable DC Pump

The Simplicity 240 employs an adjustable DC motor to operate. DC motors are more efficient and quieter than the rest.  

  • Digital Controller for Fine Tuning

An in-built digital controller is provided with the skimmer to fine-tune the motor settings and power consumption. 

  • Collection Cup with Built-in Drain

The collection cup of this unit is easy to drain and has a built-in mechanism to facilitate it more effectively. 

  • Cone Shaped Design

The proven cone-shaped design is adopted by Simplicity to create finer bubbles and collect more concentrated skimmate. 


  • Cleaning the collection cup is easy. 
  • Very low noise. 
  • Easy assembly. 


  • Pricing is on the higher side. 

5. Reef Octopus BH90

Reef Octopus BH90    

Achieving both hang-on back and cylindrical features, the Reef Octopus BH90 is one of the best-selling protein skimmers. With a reaction chamber of 4” and a height of 24”, the skimmer can serve tanks up to 100 gallons. A wet/dry adjustment mechanism is also available on the skimmer. 


  • Uses Siphon to Feed Water

Reducing pressure on the pump and removing floating oil and dirt, this unit skims the surface of the water by using a siphon to feed water to the skimmer.   

  • AQ-1000s Pump

Powerful AQ-1000s pump is capable of generating 92 GPH water flow to consistently collect skimmate. The motor is quiet and is used for its superior air-shredding technology. 

  • Turbulence Reducing Conical Body

Most HOB skimmers are square-shaped, which may help with the setting but isn’t as efficient as a conical design. The BH90 strives to become the best of both worlds.

  • Dry/Wet Adjustment Settings

The skimmer has a wet/dry adjustment setting that helps you determine the amount of skimmate you want to collect and how you want to collect it.


  • Marginally quieter. 
  • Collection cup extension hole. 
  • Cylindrical design. 


  • The instruction manual isn’t sufficient.

6. Coralife Super Protein Skimmer

Coralife Super Protein Skimmer    

Available in 3 variants, the Coralife Super Protein Skimmer can skim tanks up to 220 gallons. With its patented needle wheel system and microbubble chamber, Coralife promotes a healthy and cleaner saltwater aquarium. It can be used as a hang-on back protein skimmer with a hanging bracket. 


  • High-Functioning Foam Fractionator Design

This skimmer employs a cylindrical design and a powerful pump to fractionate dissolved organic particles and proteins in the water. 

  • Patented Needle Wheel System

The needle-wheel impeller creates an upward vortex of micro-bubbles in the skimming chamber to effectively eliminate organic compounds in the collection cup. 

  • Effortless Collection Cup Cleaning

The easy twist feature and removable collection cup make it easier for it to clean and maintain. Moreover, the durable acrylic construction of the cup also makes it dishwasher-safe. 

  • Dual Injection Inlet

Dual injection inlet increases bubble-water contact time and prevents micro-bubbles from flowing into the aquarium.


  • Quiet operation. 
  • Doesn’t release bubbles into the fish tank. 
  • East to assemble. 


  • The instruction manual isn’t adequate. Watch videos before installing it with a sump or as a hang-on back protein skimmer. 

Check out our detailed guide on ‘Aquarium Cleaning Guide‘.

7. Macro Aqua M-50 Mini Hang-on External Protein Skimmer

Macro Aqua M-50 Mini Hang-on External Protein Skimmer    

This small M-50 Mini HOB protein skimmer is one of our favorites. Efficiently cycling tanks up to 60 gallons, this macro skimmer generates a water flow rate of 238 GPH–simply removing any and every organic compound into the collection cup. Moreover, this unit is easy to use and doesn’t need any priming for it to work at its full potential. 


  • Water Flow and Air Intake Adjustment

Water flow and air intake adjustment is done by an easy-to-use dialler found on the top of the skimmer. 

  • Removable Collection Cup

A simple collection cup removal mechanism allows efficient cleaning and maintenance. You may also extend it to a bigger collection chamber by using a separate hose. 

  • Needle-to-Wheel Impeller

The needle-to-wheel impeller ensures maximum air-to-water contact, creating a huge cluster of micro-bubbles. 

  • Tough Acrylic Build

Built with premium-grade acrylic, the M-50 doesn’t corrode and create toxic substances when operated in saltwater aquariums. 


  • Quiet operation. 
  • Pricing.
  • Powerful suction.
  • Minimal Bubble release to the tank. 


  • Tough to clean the insides of the skimmer. 

8. Marine Color RDC 150

Marine Color RDC 150    

Exclusively built for smaller 40-gallon aquariums, the fashionable Marine Color RDC 150 can be used in both in-sump or hang-on back settings. Designed in red and white, in addition to being pretty efficient, it looks amazing. Moreover, air intake can be controlled in this hang-on back protein skimmer. 


  • Red Devil SP 1 Pump

With a venturi air intake capacity of 180L/H, the 12mm Red Devil SP 1 pump is virtually designed for this protein skimmer. 

  • Pinwheel Pump

Employing the concept of rotating windmills, the pinwheel pump creates a vortex of bubbles to trap and push organic compounds into the collection cup. 

  • Small Footprint

Only a 6” (with bracket) clearance is required to house and maintain the RDC 150 protein skimmer. 

  • Cast Acrylic Construction

This micro skimmer is built with high-quality cast acrylic to minimize toxin reactions and increase the operational life of the product without leakage.  


  • Significantly quieter than most skimmers. 
  • Easy setup. 
  • Great suction power. 


  • HOB clamps don’t fit standard-rimmed tanks. 
  • The collection cup is extremely small. 

9. AQUATICLIFE 115 Mini Internal Protein Skimmer

AQUATICLIFE 115 Mini Internal Protein Skimmer    

Made for 30-gallon aquariums, standing on a 3.5” base, and employing a powerful impeller pump, the AQUATICLIFE 115 Mini Skimmer delivers maximum performance with great energy efficiency. The tubeless housing design of this skimmer also makes it more appealing to beginner aquarists. 

Also, If you are a beginner, you can check out ‘Low Maintenance Fish for Your Aquarium’ here.


  • Clear Removable Collection Cup

The collection cup is easily removed and maintained. It also houses a cone mechanism to keep the skimmate from flowing back.  

  • Water Flow Control Knob

A water flow control knob is provided to set the skimmer in moderate to heavy settings, depending on the aquarium bioload. 

  • Tubeless Design

The Aquaticlife 115 adapts a tubeless design to ensure easier installation and maintenance. The only tube visible from the outside is the venturi tube. 

  • Needle-Wheel Impeller Pump

High efficient needle-wheel impeller pump is used for stronger vortex and higher protein collection. 


  • Quieter operation.
  • Easy to install. 
  • Small footprint. 


  • Ejects micro-bubbles into the tank. 

Buying Guide

If you choose to deviate from this list of the best hang-on back protein skimmers, we believe that you shouldn’t be left alone to buy something that isn’t compatible with your requirements. Therefore, we’ve made you a comprehensible buying guide that you may choose to rely upon for your future skimmer purchase. 

Tank Compatibility

Tank size is the most critical compatibility factor when it comes to protein skimmers. Depending on your tank bioload, choose a skimmer that can support your saltwater tank. Take the official numbers with a grain of salt and target products that are designed to work on a larger tank.

Although you’re in the market for HOB skimmers, don’t limit your choices to them only. Hang-on back skimmers are typically limited by their rectangular design and lack of firepower. Consider sourcing a bracket and choosing a conical product for the best result.  

Moreover, don’t forget to check the water level requirements of your preferred protein skimmer. In most cases, skimmers need a particular minimum water level to function, and having a shallower tank can deem them in operational.

Flow Control

Not every skimmer comes with a flow control mechanism, either manual or digital. But, having an air flow and water flow control system helps prevent overflow and backflow while fine-tuning the skimmer performance to not put undue stress on the pump.

Dry/wet flow control adjustments may also be critical if you have high-bioload tanks.

With excessive water flow, some saltwater species, such as corals, can be affected. Optimal flow control ensures safe yet effective operation. On the other hand, you can increase the flow to adapt to bioload changes without investing in different skimmers. 

As a bonus, a reduced flow may also reduce energy consumption. 

Noise Level

Hang-on back skimmers generally are noisier than in-sump or internal skimmers. However, with submersible motors, the noise can be reduced to bare humming. While you may hear the sound of the bubbles forming with a premium skimmer, that isn’t comparable to deafening motor noises. 

Additionally, DC motors are quieter than impellers and other variants. 

Online Reviews

Always rely on verified online reviews when choosing a HOB skimmer. Do consider positive reviews, but always skim through the negative ones to get a general idea about the product. 

Keep an eye out for common issues that may be occurring while considering sporadic challenges that a few customers have faced.  


Skimmers aren’t cheap. As they usually don’t require any additional accessories, do try to choose the best one that your budget can buy. While choosing one, buy one that’s rated for a bit higher tank size, but don’t go overboard to the extent of wasting resources and money.  


1. What are protein skimmers? 

Protein skimmers are saltwater equipment that eliminates floating organic compounds from the water through a physical phenomenon called surface tension. Bubbles accumulate hydrophobic organic compounds on the surface to create a frothy mixture called skimmate. 

2. How do protein skimmers work? 

Protein skimmers create bubbles inside the reaction chamber to attract hydrophilic (water-attracted) and hydrophobic (air-attracted) organic molecules to dump into the collection cup. 
Absorption, the affinity of hydrophobic compounds for air-water interfaces, is also used in protein skimmers for more efficient operation.

3. Do you still need a filter if you have a protein skimmer installed?

Yes, mechanical and biological filters are needed even if you have a skimmer installed. The filters disintegrate toxins compounds such as ammonia and nitrite to keep water quality in check, while the skimmer separates visible organic particles from the water body. 

The Bottom Line

Skimmers are essential components in a saltwater setup. We’ve enlisted the 9 best hang-on back protein skimmers available online and have tried to give you an outline of features and tips that may help you choose your own.

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