Last Updated on April 24, 2023 by Coral Realm

Aquariums are brilliant additions to any home. Not only do they look amazing and allow for a fantastic display of fish and aquatic plants, but they also bring a range of health benefits. 

Cleaning the fish tank is an essential part of maintenance, which is why your tank needs a good filter. There are a few different filter types that you can choose from; canister filters, under gravel filters, sponge filters, or as we will discuss in this article, the HOB filter. The filter will clean the water, while you use an aquarium vacuum cleaner to clean the substrate.

HOB filters offer a brilliant way to provide your aquarium and the fish that live there with clean and clear water. They are one of the most popular filter types, and by the end of this article you will be able to see why!


List of the Best HOB Filters

What is a HOB Filter?

HOB is an abbreviation of hang on back. These filters are called this because they simply hang on the side of the aquarium glass, rather than being housed underneath or next to the fish tank like a canister filter. HOB filters are also commonly known as power filters.

Hang on back filters draw water from the aquarium through an intake valve, which then passes over the filtration media. The filter media is housed in the body of the filter. As HOB filters aren’t too large, the amount of filter media that can be contained in the body is limited.

As such, the capacity of hang on back filters are lower than canister filters, but in general they offer better filtration power than sponge filters. They are often used for smaller aquariums.

The filtration media can come in the form of mechanical, biological, and chemical media. Mechanical media are usually in the form of pads and sponges, which physically trap larger floating debris and detritus. Biological media provide a place for beneficial bacteria growth. These bacteria remove dangerous compounds such as ammonia, nitrite, and nitrate from the water column. Chemical media remove toxins and discolorations from the water column. Activated carbon is the most common form of chemical media, but there are other varieties on offer as well, such as Seachem Purigen.

How To Choose The Best HOB Filter

Before we get into the best HOB filter reviews we will run over what features you should be looking at when choosing your HOB filter, so you can easily choose the best HOB filter for you. 

Size of your tank

If you don’t know the size of your tank you should check and find out. It is most common to say what size tank you have in gallons; the amount of water your tank holds. 

The size of your tank will tell you what size and power of filter that you need. Smaller tanks will be able to be cleaned with smaller filters, whilst larger tanks will need larger filters. 

What will also affect the size filter you require will be the bioload of your tank. The bioload is how many fish and aquarium plants you have in relation to the size of your tank. If you have lots of  fish for the size of your tank you will need a higher powered filter than you might initially think in order to handle the amount of waste they produce.

Flow rate and capacity

The flow rate of an aquarium filter is measured in gallons per hour, or GPH for short. This denotes the volume of water that the filter can pump out each hour. It therefore gives an indication of how much water it can clean in an hour. 

The capacity of a filter is what size tank that filter is designed for. For instance a filter with a capacity of 100 gallons could be used on tanks of 100 gallons or less.

You should be looking for a HOB filter with a flow rate approximately three times the size of your tank. If you have a tank of 40 gallons, a filter with a flow rate of 120 GPH should suffice, unless you have a high bioload, in which case you should get a slightly higher flow rate filter. You want the flow rate to be at least three times the tank volume so that all the water in the tank passes through the filter three times in an hour. 

Three stage filtration

We have spoken about how there are three types of filtration media available to put into aquarium filters, HOB filters included. These are mechanical, biological, and chemical filtration. A filter which offers all three of these filtration is said to have triple stage filtration.

Triple or three stage filtration is the top end of filtration that you can get from a fish tank filter. The workings of mechanical, biological, and chemical media in tandem provide cleaning many times stronger than any of these on their own.

Wherever possible, you want your HOB filter to possess triple stage filtration.

Best HOB Filter Reviews

Best HOB Filter Reviews

Now that you have an understanding of what an aquarium HOB filter is and how to choose the best HOB filter appropriate for your tank, we can dive right into our list of the best hang on back filter reviews.

1) Fluval C4 Power Filter

Fluval C4 Power Filter, Fish Tank Filter for Aquariums up to 70 Gal.
  • 5-stage clip-on power filter designed for freshwater and saltwater aquariums between 40 and 70 gallons
  • Two mechanical stages trap large and fine debris, foams easily slide out for quick cleaning
  • Chemical stage with activated carbon effectively removes toxins
  • Biological stage features Bio-Screen pad, blocks debris and provides massive surface area for beneficial biological activity
  • Biological Trickle Chamber super charged for fast and efficient nitrification when loaded with Fluval C-Nodes

The Fluval C4 Power Filter is a brilliant hang on back filter for aquariums of between 40 and 70 gallons. The flow rate is 264 GPH, so it is a very powerful HOB filter. The Fluval C4 Power Filter is the largest and most powerful of the C series filters. If you have a smaller tank you can instead choose the C2 or C3 power filter. The C2 Power Filter is designed for tanks between 10 and 30 gallons, and has flow rate of 119 GPH; while the Fluval C3 Power Filter is designed for tanks between 20 and 50 gallons and has a flow rate of 153 GPH.

The brilliant thing about the Fluval C4 HOB filter is that it offers five stage filtration. If you remember further up in the article we said you want to be on the lookout for triple stage filtration; five stage goes two better! These stages include two mechanical filtration media, two biological media, and one chemical media stage. The two mechanical media are sponges of differing porosity, designed to capture both large and small floating debris. These five stages of filtration offer the filtering capacity to rival canister filters!

With independent stage management you have easy access to each filtration stage and media independently of the others. This makes cleaning and maintenance much easier than with most other HOB filters, where you need to remove all media to just change a small part. 

Maintenance is incredibly easy with the C4 Power Filter as it possesses quick release media cartridges which allows you to easily access to clean or replace the cartridge.

The footprint of this HOB filter is very small, so you don’t have to have a huge amount of space around your aquarium in which to install it.

A brilliant feature in the Fluval C Series Power HOB Filters is the patented filtration control system. On the shell of the filter there is a switch which allows you to slow the release of water back into the tank, and also to increase the dwell time of water in the filter body. This means that as the water spends more time in the filter it has more exposure to the media and therefore can be cleaner when it returns to the tank. The slower release of water is perfect for fish such as Betta fish which like low water movement.

2) Penn Plax Cascade Hang On Back Filter

Penn Plax Cascade Hang On Back Filter
  • QUIET & EFFICIENT: The Cascade 300 Power Hang-On Filter quietly delivers crystal clear water throughout the aquarium. This filter pushes water at 300 Gallons per Hour (GPH) for tanks up to 100 Gallons in size. It’s great for Freshwater and Saltwater aquariums.
  • ACCOMMODATING: The adjustable flow knob allows for increased or decreased water flow at will, which is extremely helpful during feeding times, or use it as needed. The hang-on design is constructed for safe mounting. The lift tube extends between 8. 25” (min) and 12. 25” (max). Please be aware that the filter indeed does make some noise.
  • EXTREMELY BENEFICIAL: This Cascade filter utilizes disposable, double-sided media cartridges that contain Activated Carbon and Poly Fiber Floss. The included cartridge traps floating particulate matter, removes harmful chemicals and toxins, clears up discolorations, and reduces foul odors from your aquarium’s water. Media cartridges are recommended to be replaced once a month.
  • REVOLUTIONARY: The Cascade 300 Power Hang-On Filter features a Bio-Sponge cartridge that optimizes colonization of anaerobic bacteria, and is independent from the first stage filter media. In addition, our Bio-Falls system enhances water oxygenation, and aids with removing ammonia and nitrate.
  • OVERALL MEASUREMENTS: 8. 25” (H) x 11. 25” (W) x 6. 25” (D)

The Penn Plax Cascade Hang On Back Filter is another brilliant HOB filter worthy of the number two spot on this list. There are six models available of varying power options offering flow rates from 20 to 300 GPH, and designed for aquariums of 7 gallons up to 100 gallons. The Penn Plax Cascade 20 is the smallest, with the Penn Plax Cascade 300 the largest. This flexibility of size options is a real plus point, as you can choose exactly the size you need for your individual tank setup. 

Continuing from the flexibility of power options, the Penn Plax Cascade Hang On Back FIlter features an adjustable flow knob which enables you to lower the flow as and when you need. During feeding times it is especially useful, or for if you feel the flow is too high for your tank. 

The Penn Plax Cascade Hang-On Back Filter utilizes a revolutionary bio-falls quad filtration system which includes a bio-sponge cartridge which enables and promotes the growth of anaerobic bacteria which can remove nitrate as well as harmful toxic ammonia and nitrite from the water column.

This filtration system features all of mechanical, biological, and chemical media. Disposable media cartridges are used which are doubled sided; they contain both polyfiber floss and activated carbon. This allows for the power of triple stage filtration whilst being very easy to clean and replace. The bio-falls system also increases water oxygenation.

It is incredibly easy to set up and install, and is also designed to be very quiet when operational.

3) AquaClear HOB Filter

AquaClear 110 HOB Filter
  • Aquarium filtration system that offers superior contact time with filter media and energy efficient pump lowers operating costs
  • Quick and easy installation; we recommend that you clean aquarium filter every 2 weeks for maximum operation and efficiency
  • Provides optimal mechanical; chemical; and biological filtration
  • Comes equipped with AquaClear Foam; Activated Carbon Filter and BioMax and Cycle Guard for superior water quality
  • Filtration volume is up to 7 times larger than comparable fish tank filters

The AquaClear HOB filter can be found in five different size and power models; smallest is the AquaClear 20, then the AquaClear 30, AquaClear 50, AquaClear 70, and the AquaClear 110 power filter. The AquaClear 20 has a capacity of between 5 and 20 gallons with a flow rate of 100 GPH, the AquaClear 30 has a capacity of between 10 and 30 gallons with a flow rate of 150 GPH, and the AquaClear 50 has a capacity of 20 – 50 gallons, and has a flow rate of 200 GPH. If you have a larger tank the AquaClear 70 has a 40 to 70 gallon capacity with a 300 GPH flow rate whilst the AquaClear 110 has a capacity of between 60 and 110 gallons, with a flow rate of 500 GPH.

The AquaClear HOB filter features a unique and patented design which allows for up to six times the amount of media volume compared to basic HOB filters. This design also provides increased contact time between the water and the filter media for increased filtration. 

Triple stage filtration is featured in the AquaClear HOB filter. Mechanical media is in the form of the AquaClear Foam insert, which removes floating debris and allows the subsequent filter media to function at full efficiency by preventing clogging and optimizing water movement patterns. The porous nature of the media pad also provides space for bacterial colonization to provide biological filtration as well. Activated carbon is the chemical media, and further biological filtration is offered through biomax ceramic rings.

All basic filtration media is included, but if you want to modify the media to fit your tank needs perfectly AquaClear offers an extensive line of media including Zeo-Carb and Ammonia Remover.

The flow rate can be reduced in the AquaClear Power Filters. This is incredibly useful as you can modify the flow as and when to suit your needs. If you reduce the flow rate, then water will run through the filtration media multiple times, meaning cleaner water and a clearer tank.

The waterfall design of the outlet increases aeration and oxygenation of the water column, while ensuring near silent flow of water back into the tank.

4) Seachem Tidal Power HOB Filter

Seachem Tidal Power Aquarium Filter - 35 Gallon Large Fish Tank Filter,black
  • FLOW REGULATION: The fully adjustable flow regulation feature on the Tidal Power Filter adjusts performance to a specific aquarium volume, type, or...
  • SURFACE SKIMMER: The surface skimmer on the Tidal Power Filter will capture the water from just below the surface, where excreted fish oils...
  • ADJUSTABLE INTAKE FLOW: With Tidal’s dual intake, it pulls water in through the telescoping pipe below the surface and at the surface through the...
  • HEATER HOLDER: A heater can be attached to the side of the Tidal Power Filter with an optional heater clip, allowing for better dispersal of heated...
  • MAINTENANCE ALERT: When filtration media becomes clogged with detritus and affects the flow of water, the Tidal Power Filter redirects water around...

The Seachem Tidal Power HOB Filter comes in four different power and capacity options. This ranges from the Seachem Tidal 35 which has a capacity of up to 35 gallons and has a maximal flow rate of 130 GPH, while the largest, the Seachem Tidal 110 has a capacity of up to 110 gallons with a flow rate of 450 GPH.

This flow rate can be further adjusted on each model; the adjustable flow feature enables you to increase or decrease the flow rate as you wish. This feature has many different uses, from allowing uninterrupted feeding to allowing certain fish to feel more comfortable.

The Seachem Tidal Filter features a surface skimmer intake as well as a deeper water intake. Fish oils accumulate just below the surface, so taking surface water as well as deeper water ensures that the tank water is cleaned to the fullest. An intake flow valve enables you to adjust how much water is drawn through each of the surface and deep water intakes. 

Maintenance alerts are given when the filtration media becomes clogged with debris and flow begins to be affected. It is cleverly done; when the filter is clogged water flow is redirected around the media and through an outlet at the side, where it pushes the blue indicator up.

All of these additional features are brilliant, but the Seachem Tidal Power Filter is also brilliant at its most basic function. Offering triple stage filtration it provides excellent filtration capacity for your tank.

5) MarineLand Penguin 350 Power Hang On Back Filter

Marineland Penguin Bio-Wheel Power Filter
  • WITH ROTATING BIO-WHEEL: Patented Bio-Wheel technology provides excellent wet/dry biological filtration.
  • MULTI-STAGE FILTRATION: Delivers mechanical, chemical and biological aquarium filtration to maintain a clean aquatic environment.
  • COMPATIBILITY: Use with Marineland Rite-Size Filter Cartridges (see individual filter for sizing recommendations).
  • FIVE SIZES: Available in 75 GPH, 100 GPH, 150 GPH, 200 GPH and 350 GPH sizes.
  • Age range description: All Life Stages

The MarineLand Penguin HOB Filter is a brilliant filtration system for all fish tank setups. It is available in five different size and power options; therefore is suitable for aquariums ranging from 10 to 75 gallons. The MarineLand Penguin 100 is the smallest with a flow rate of 100 GPH, and a capacity of 10-20 gallons. Largest is the MarineLand Penguin 350 HOB Filter with a capacity of 50 to 75 gallons with a flow rate of 350 GPH. 

The MarineLand Penguin 350 offers triple stage filtration in the form of filter cartridges containing filter floss for mechanical filtration and activated carbon for chemical media. Biological filtration is found through the patented BIO-wheel. This BIO-wheel now has 50% more surface area and provides the ideal place for nitrifying bacteria to inhabit which will remove toxic ammonia and nitrite from the water column. The filter cartridges are found ready to install with each newly purchased filter.

Installation is very simple; all you need to do is find  the perfect spot on the glass of your aquarium. Priming is the only downside; you need to fill the chamber of the HOB filter yourself with water before startup.

Maintenance is very easy with the two-piece vented cover. It is designed to allow for easy filter cartridge access to easily clean or replace the cartridges and to also clean the filter body.

The intake tube is adjustable which allows you to find the perfect level for it. Being able to adjust it like this enables improvement to the water circulation.

A common issue with the MarineLand Penguin 350 seems to be the filter making excessive noise. There can be actions which can be undertaken to reduce filter noise, but do bear this in mind.

6) Tetra Whisper EX Power Filter 

Tetra Whisper EX 70 Power Filter
  • WHISPER QUIET The Tetra Whisper EX Power Filter provides silent multi-stage filtration for clear clean water .SIZE This filter fits 45 to 70 gallon aquariums - 240 GPH
  • FAST SETUP Sets up easily right out of the box – no priming required
  • CONTINUOUS FLOW Moves water continuously to prevent debris buildup
  • NO-MESS FILTER CARTRIDGE CHANGES Design minimizes dripping to make cartridge changes easy
  • SIZE This filter fits 45 to 70 gallon aquariums - 240 GPH

The Tetra Whisper EX Power Filter is a brilliant hang on back filter which comes in four power options which offer different capacities. The smallest has a capacity of between 10 and 20 gallons, with a flow rate of 110 GPH. The largest has a capacity of between 45 and 70 gallons and has a flow rate of 340 GPH. Having a choice of four different size options enables you to choose the most appropriate power option for your fish tank setup.

The Tetra Whisper EX Power Filter offers powerful triple stage filtration. Multiple densities of filter floss enable the effective capture of both large and fine floating debris particles. The activated carbon inside helps to eliminate odors and discolorations, while the bio-scrubber provides a site for bacteria colonization which removes toxic ammonia and nitrite. 

Your aquarium water is designed to be moved continuously with the Tetra Whisper EX. This maximizes the oxygenation of the water. The motor is quiet but very effective.

Maintenance is very simple and easy. The Tetra Whisper EX70 uses Tetra filter cartridges which are put into a handy carrier. This carrier can easily be removed to replace the filter cartridge. Timestrips tell you when it is time to change the cartridges.

Our Recommendation for the Best Hang On Back Filter

Whilst the best HOB filter will entirely depend on your personal aquarium setup, and any of the six filters listed here will do a brilliant job, we do have a favorite. For us, it is the Fluval C4 Power Filter.

Whilst all these HOB filters offer multi-stage filtration, the Fluval C4 HOB Filter is the only model to offer powerful five stage filtration. 

This hang on back filter provides unparalleled filtration power, and also offers an option to reduce output flow whilst increasing water dwell time in the body of the filter. 

The Penn Plax Cascade and the AquaClear HOB Filter run it very close though!

How to Install a HOB Filter

Installing a hang on back filter is quite simple. Each filter will come with its own instructions and individual specifics, but in general all will follow the same basic principles.

Step 1: Check the filter for any breakages. It is always worthwhile to spend a good few minutes making sure that everything has been packed and nothing has cracked during transit. There’s nothing worse than completing setup, then finding out it’s cracked when there’s water all over the floor!

Step 2: Add and layer the filtration media. Many hang on back filter manufacturers will include the required filtration media. However if they don’t then you will need to purchase the media yourself. Once you have the media you will see that there is space in the body of the HOB filter to house the filter media. Add the media so that the water runs over the mechanical media first. Second should be the biological media. Finally the chemical media last.

Step 3: Attach the HOB filter to the tank. HOB filters simply hang on the aquarium glass, hence the name hang on back. So find the appropriate bit of the tank glass for the filter to hang on too. Normally the back of the aquarium is preferred so it is least likely to be in direct eyeline.

Step 4: Plug in the HOB filter. Plug the hang on back filter into an electrical outlet and turn it on.

Step 5: Prime the filter. Different HOB filters will have different means of priming the systems. As HOB filters are reasonably small this shouldn’t be too much trouble. In the main hang on back filters are self priming, and don’t cause any trouble!

Step 6: Use an aquarium bacteria supplement. Adding a dose of aquarium bacteria supplement will allow the bacteria in these supplements to quickly colonize the biological media, as well as the mechanical media. This will work to ensure full filtration capacity as soon as possible.

Hang On Back Filter FAQs

In this section we will run through a few of the most frequently asked questions about hang on back filters.

Can HOB filters be used in saltwater tanks?

Hang on back filters can absolutely be used in saltwater tanks. Unless a HOB filter has directly been specified as only for freshwater use then they can be used in saltwater tanks without any issue whatsoever.

If you plan on using a HOB power filter in a saltwater tank setup, don’t forget that you still need to install a good protein skimmer to remove the dissolved proteins from the water column that a filter won’t remove. Remember that this is the case even if you install a larger capacity canister filter. 

Are canister filters or HOB filters better?

The answer to this question depends on the unique fish tank setup that you have; you could be better suited with a HOB filter or a canister filter depending on the size, depth, and bioload of your aquarium. 

You can read our article on canister filters vs power filters for full information. 

In general, canister filters are better for high bioload tanks or large tanks of 100 gallons or more. As canister filters sit outside the tank, they can be hidden from view and if you have your tank in a tight space can be placed underneath the tank in a cupboard for instance.

HOB filters are best suited for smaller tanks or tanks with a small bioload. As they have much less physical space to house filtration media they cannot handle as much waste as canister filters. Also as they are smaller the pumps which run them are less powerful, meaning that they cannot clean as much water per hour as the equivalent canister filter.


Hopefully this article of the best HOB filter reviews has been informative and helpful. HOB filters are brilliant for smaller tanks of, in general, 100 gallons or less. 

You should now know what to look for in a hang on back filter and how to install them in your aquarium. Hopefully the reviews have been useful to you as well and you have a better idea of which aquarium filter you might be going for!

Happy filter hunting, and please leave a comment if you have any questions!

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