A hang on back refugium can be a GREAT addition to your tank.

It’s typically used to keep more sensitive or smaller fish.

It can house plants, live rocks, beneficial microorganisms and sand.

And you can also use it to enhance biological filtration…

… through the development of microalgae and healthy bacteria.

To get the best hang on back refugium on the market?

Check out our selection below!


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Why We Love it:

  • Easy setup

  • Perfect for larger tanks

  • Unique baffle system



CPR AquaFuge2 is designed to provide a controlled growing area for microalgae and other food items, but it comes with a wealth of additional benefits. Thoughtfully laid out to fit in constricted spaces; it can provide a healthy flow of water and stabilize your aquarium ecosystem.

Coming in three sizes, it impresses with an innovative design with a black back that prevents the light transfer between the refugium and the tank.

Superior quality build and easy set up make it a favorite among beginners and expert fish keepers alike. It’s designed for multiple media, but don’t expect it to give its best if you’re planning to use it with mechanical filtration media.

Equipped with a powerhead and featuring a unique baffle system, it also provides outstanding water flow without disturbing the substrate or organisms.

Fairly quiet and easy to maintain, it’s undeniably a great choice for aquariums of all sizes. If you want something that doesn’t have such a steep price tag, the next hang on back refugium might be a better option for you.

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Why We Love it:

  • Multifunctional add-on

  • For fresh and saltwater systems

  • Great value for money



If you’re looking for a multifunctional aquarium add-on that won’t cost you an arm and a leg, chances are you’ll like the Finnex External Hang-on Box.

This refugium is designed for those short on space. Serving a host of purposes, you can use it for breeding fish or growing algae. Regardless of your purpose, the refugium comes with all accessories you might need, including a nano water pump.

One of its main benefits is the lower flow, which gives fish a stable breeding or growing environment.

Ideal for both fresh and saltwater tanks, it can also be used for growing pods and cheato if you plan to use it as a refugium filtration system.

It also mounts easily and fairly secure and can be placed on your sump or main aquarium. No doubt, a hang-on back refugium that brings true value for money.

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Why We Love it:

  • Black back

  • Odyssea 250 pump included

  • Perfect for mid-sized tanks


Next entry on our list of the best hang on back refugium, this tank by Blue Ocean can be a great nursery or isolation area, controlled area for your microalgae, or food growing area for species like copepods and amphipods.

Ideal for 50 to 60-gallon tanks, it also comes with an Odyssea 250 pump. However, it doesn’t include the light.

Like most hang-on refugium models, it’s easy to mount. The only drawback is the slightly flimsier acrylic that’s easy to break. It also has a louder pump.

Similar to the AquaFuge 2, it has a black back to prevent the transfer of light to the main tank. Greatly priced for its size and super-efficient overall, it’s a great alternative to consider if you look for a more-wallet friendly refugium system.

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Why We Love it:

  • Wallet-friendly hang-on back refugium

  • Durable acrylic

  • Space-saving design



Affordable yet reliable, the Marina Hang-In Breeding Box appeals to fish keepers on a budget. It doesn’t come with any bells and whistles, but you can use it for a variety of purposes. Indeed, the box provides a safe and secure area for acclimating, breeding, or isolating your fish or growing plants.

It has a space-saving design and comes in three sizes. Clear walls designed for easy viewing and easy maintenance bring further value for money.

This box is compatible with both framed and frameless aquariums with a glass thickness of at least 5mm. Included partition plates also give you the possibility to divide the box into different compartments and use it for multiple purposes at the same time.

You will need to purchase a small water pump, connector tubing and light separately, but with some modifications, it can be a useful addition to your tank. One thing to note is that it does seem to be prone to overflowing, so the incoming water flow must be carefully monitored during the first hour of setup.

It might have some overflow issues if you’re not careful when you set it; all in all, though, this hang-on breeding box is a great choice for the price.

Tips for Choosing A Hang On Back Refugium

Depending on the model you like…

… a hang-on back refugium can be an important investment for your aquarium.

If you don’t want to waste your money,

You should check these things before buying:

  • Size: The market offers a bountiful range of hang-on back refugium models of different sizes, and it’s a good idea to match its size with the size of your aquarium. A good rule of thumb is to get a refugium that’s about ¼ the size of your tank, especially if you want to use it for biological filtration. But bigger is even better.
  • Versatility: Some refugium models come with partition plates that allow you to divide the space into chambers and use the box for more purposes at once. Undoubtedly, something to consider if you want to both breed fish and grow microalgae, for example.
  • Durability: A hang-on back refugium must be lightweight; that’s why most models are made from acrylic. It is good, however, to check the overall build quality and durability of the tank before buying.
  • Accessories: Accessories can also make or break the deal. Some refugium models may seem expensive, but they come with all the accessories you need, including a pump and light. Some refugiums might seem affordable at first glance, but if they come with no accessories, you could spend more overall.

Interestingly enough:

Testing is indicative that HOB refugiums ARE effective at reducing nitrates & phosphates in an aquarium:

Related Post: Freshwater Refugium Filters

Over to You

Which is the best hang on back refugium is ultimately up to you and your needs.

Do you need a full system comprising the tank and accessories?

Or just a replacement box for a broken or damaged refugium?

Whichever your choice, I hope you could find the right refugium for you on this list.

So, what do you say?

What do you plan to use your hang on back refugium for?

Tell me in a comment below; I’d love to hear from you.

And if you liked this article…

… don’t hesitate to share it with your friends.