Updated: February 9, 2023 - By: - Categories: Equipment

Also known as power filters, hang on back (HOB) filters are a basic recirculating water filter design that was created specifically for aquarium hobbyists in mind. They are great for beginner aquarists, especially if you are starting small.

Best HOB filter comparison table

Model Our rating Type Flow rate For tanks Media Other options
nano aquarium filter for aquarium up to 3.5 gallons editor's ratingAZOO Mignon Filter 60 #ad HOB adjustable Betta, shrimp, nano tanks up to 3.5 gallons foams, pre-filter sponge Azoo Mignon Filter 150
EA Performance HOB filter editor's ratingEA Performance HOB filter #ad HOB adjustable nano fish tanks up to 4 gallons, Betta fish foams
Marina S10 Power Filter editor's ratingMarina S10 Power Filter #ad Hang-On-Back 55 GPH, adjustable up to 10 gallons (10-20 Gal available) filter cartridges with included carbon & zeolite Marina Slim S15 (to 15 Gal), Marina Slim S20 (to 20 Gal)
Aqua Clear 20 power fish tank filter editor's ratingAqua Clear 20 power filter #ad Hang-On-Back 100 GPH, adjustable 5-20 gallons (5-110 Gal available) Foam, Activated Carbon, and BioMax AquaClear 30 (150 GPH) – AquaClear 110 (500 GPH)
Tetra Whisper 20 Power Filter editor's ratingTetra Whisper 20 Power Filter #ad Hang-On-Back 105 GPH, adjustable 10-20 Gal bio-foam, large Bio-Bag cartridge Whisper 10 (90 GPH) – Whisper 60 (330 GPH)
Aqueon QuietFlow 30 power filter editor's ratingAqueon QuietFlow 30 power filter #ad HOB with cleaning LED indicator 200 GPH, adjustable 30-45 gallons large Aqueon replacement cartridge QuietFlow 10 (100 GPH) – QuietFlow 75 (400 GPH)
Penn-Plax Cascade 200 Hang-on Aquarium Filter editor's ratingPenn-Plax Cascade 200 Hang-on Aquarium Filter #ad Hang-On-Back 200 GPH, adjustable 35-55 Gal carbon cartridge, bio-sponge Cascade 20 – Cascade 300
Marineland Penguin 350 Bio-wheel power filter editor's ratingMarineland Penguin 350 Bio-wheel #ad Hang-On-Back 350 GPH up to 50-75 gallons rotating bio-wheels, filter cartridges with included carbon Penguin 75 – Penguin 200
Fluval C4 Power Filter editor's ratingFluval C4 Power Filter #ad HOB 264 GPH (1000 L/h) 40-70 gallons (265 L) floss pad, foam, activated carbon, others Fluval C2/C3
SeaChem Large Aquarium Fish Tank Filter editor's ratingSeachem Tidal 110 #ad HOB with surface skimmer 450 GPH (1000 L/h), adjustable up to 110 gallons (400 L) foam, Seachem’s Matrix™ bio-media Seachem Tidal 35 (130 GPH) – Tidal 75 (350 GPH)
Tetra Whisper EX70 editor's ratingTetra Whisper EX70 #ad HOB 340 GPH up to 70 gallons large Whisper EX carbon cartridge Whisper EX20 – EX70
Hygger hang-on power filter editor's ratingHygger hang-on power filter #ad HOB with surface skimmer 158 GPH, adjustable 30-gallon sponge, activated carbon, bio balls

Hang-On-Back filter review

AZOO Mignon Filter 60 for nano fish tanks under 3.5 Gal

This quiet filter is perfect for a nano aquarium up to 3.5-gallons with small fish and shrimp. It comes with a sponge pre-filter to cover the water inlet to prevent drawing up any small aquarium inhabitants.

Water intake with pre-filter spongeWater intake with pre-filter sponge #ad

Inside its “clear smoke” plastic housing is ample space for two filter pads, one mechanical foam pad and one biological foam pad, that are easy to replace. There is even extra space for additional bacterial filter media if desired.

It has a flow rate of up to 16 GPH (gallons per hour), which can be controlled with an adjustable flow control dial. This also helps maintain high dissolved oxygen levels.

The AZOO Mignon Filter 60 also has a small fine filter pad that divides the pump and media compartments. This filter pad helps finely polish the water as well as helps aid the pump in self-priming after a power outage.

The pump is easy to access and remove for easy cleanings.

EA Performance Hang-On The Back Power Filter – Up to 4 Gallons

The EA Performance power filter is rated for aquariums up to 4-gallons and would be great on a nano shrimp aquarium.

EA Performance HOB filterEA Performance HOB filter #ad

It has a simple two-stage filtration, with a mechanical filter sponge and a biological filter sponge. The flow can easily be adjusted with the flow control valve.

Its intake tube assembly comes with an extension tube, to lower the intake deeper into your aquarium.

This filter is easy to maintain as well as simple to clean. It also comes almost completely assembled in the box, for a simple “plug and play” setup.

Marina Slim S10 Filter for tanks up to 10 gallons

The Marina Slim S10 filter is rated to fit aquariums up to 10-gallons. Its filter box is designed to have a slim profile to help create a minimalist, sleek look.

Instead of the pump being attached on the outside of the filter, like most HOB filters, the Marina Slim S10 places the pump inside the aquarium, attached to the intake tube. This helps reduce the amount of noise created by the pump, making it much quieter than other filter brands.

Also, having the pump in the aquarium helps the pump to easily prime itself after a power outage or after cleaning. The flow can easily be adjusted with its flow control valve.

Bio-Carb and Bio-ClearBio-Carb and Bio-Clear #ad

This filter has room for two filter cartridges and comes equipped with one Bio-Clear cartridge and one Bio-Carb cartridge, both filled with Marina’s Ceramitek porous media for optimal biological filtration.

It also comes with a circular foam pad pre-filter to cover the intake to the pump, helping reduce sucking up fish and helping filter out large debris.

Aquaclear 20 power filter for 5-20 gallon fish tanks

This filter (or series of filters) is one of the most versatile HOB filters on the market today. Its large capacity and patented re-filtration method allow for up to six times more media space and a longer contact time with the filter media.

Multi-stage filtrationMulti-stage filtration #ad

The best feature of the AquaClear Power filters is that the media isn’t in cartridge form, like most aquarium filters. Instead, it’s all separate, which allows for multistage filtration and gives you the option to modify your filter media combination to suit your specific aquarium needs.

The AquaClear 20 Power filter comes equipped with a foam insert, that should be placed on the bottom of the media basket, which filters large particles and helps divert the water equally through the rest of the media. The foam insert is also a highly porous surface, providing lots of space for healthy bacteria growth.

Next is the activated carbon bag that provides ample surface area for absorption of water impurities, like odors, chemicals, or medications.

After the carbon bag is the BioMax filter that is full of highly porous ceramic rings that provide even more surface area for beneficial bacteria growth.

The AquaClear 20 Power Filter is suited for aquariums up to 20-gallons and has a flow rate of 100gph.

Tetra Whisper 20 power filter for 10-20 gallon tanks

The Tetra Whisper Power Filter 20 is a great economical HOB filter for a 10- to 20-gallon aquarium, with an adjustable flow rate of up to 105 GPH.

It incorporates a 3-stage filtration system with a double-sided dense mesh filter cartridge filled with Ultra-activated carbon, and a Bio-foam pad for bacterial filtration.

The cartridges are easy to replace, and either come pre-assembled for ease, or un-assembled for half the price.

Aqueon QuietFlow 30 power filter

Aqueon’s QuietFlow LED Pro aquarium power filter series is the Cadillac of HOB filters. They have a red LED indicator light that flashes when the filter needs to be changed, all by monitoring the water level in the filter.

They also have the pump placed inside the aquarium attached to the water intake tubes. This gives them a self-priming capability and will auto-start when plugged in or in case of a power outage.

Multi-stage filtrationMulti-stage filtration #ad

This filter has a unique 5-stage filtration process. This multi-stage filtration design makes filter changes simple but prevents the loss of beneficial bacteria when replacing the filter media.

The dense floss filter cartridge, which is filled with activated carbon, is designed to help physically remove all debris particles and toxins, odors, and help with clarity.

The Patented Bio-Holster (the blue plastic holster that holds the cartridge) is to help encourage beneficial bacteria growth, as well as remove ammonia and nitrites.

The diffuser grid with a honeycomb pattern, which provides more surface area for bacteria growth and increases dissolved oxygen in the water. It also has the added benefit of reducing splashing noise from the water waterfalling back into your aquarium.

The filter is also compatible with Specialty filter pads from Aqueon. These are foam pads coated with filter materials like ammonia remover, activated carbon, or phosphate remover.

Penn-Plax Cascade 200 hang-on aquarium filter

The Penn-Plax Cascade 200 HOB filter is rated for aquariums up to 55-gallons, with a flow rate of 185gph.

This filter has a 4-stage filtration system starting first with a double-sided filter cartridge, one side poly-fiber floss, the other filled with activated carbon.

After the filter cartridge is the Bio-sponge, independent from the cartridge and permanent, to encourage healthy beneficial bacteria growth.

Penn-Plax Cascade 200 Hang-onPenn-Plax Cascade 200 Hang-on #ad

The final filtration stage is the Bio-fall wet/dry filter that trickles the water through a zip-zag pattern to increase oxygenation of the water and promote more nitrifying bacteria to grow.

Other features of this filter are an adjustable flow control valve and the option of an extendable intake tube for deeper filtration.

Marineland Penguin 350 Bio-wheel power filter

The Marineland Penguin 350 power filter is a classic large HOB filter that also incorporates a wet/dry filtration method. It has the basic 3-stage HOB filter design, with the pump attaching to the filter box that hangs on outside the aquarium.

Bio wheelsBio wheels #ad

The most special stage of filtration on the Penguin 350 power filter is the two wet/dry Bio-Wheels that spin as the water is pushed over them. This spinning while being wet helps increase oxygen and promote the growth of helpful nitrifying bacteria, which boosts the nitrogen cycle.

Rite-Size C cartridgeRite-Size C cartridge #ad

Refillable media cartridgeRefillable media cartridge #ad

Besides, it also provides two-compartment spaces to accommodate at least two Rite-Size C filter cartridges, with additional space for any modifications, like the refillable media cartridges by Marineland.

The Rite-Size C filter cartridge is a poly floss pad on one side with a rigid plastic backing that is filled with activated carbon.

It also comes with an adjustable mid-level intake flow valve that allows for flow control but also helps with circulation in the middle of large aquariums.

Fluval C4 power filter for 40-70 Gal

The Fluval C4 Power Filter is a very cleverly designed HOB filter that incorporates a 5-stage filtration system with a wet/dry trickle filter.

Five filtration stagesFive filtration stages #ad

Patented refiltration systemPatented refiltration system #ad

As it turns out Fluval and AquaClear products are owned by the same company, so the Fluval C Series Power Filters are essentially the updated version of the AquaClear Power Filters.

Just like the AquaClear filters, the Fluval C4 has the same patented refiltration system that diverts 50 percent of the water to recirculate back through the stage one mechanical filter pads.

The Fluval C4 doubles up on the mechanical filter media, one foam pad for large debris, and one dense floss pad for fine debris. These two filters are slid into an easy-pull plastic cage, which makes filter cleaning easy.

A unique feature of this mechanical media basket is a pop-up cleaning indicator. This tab will pop-up when the water flow rises, indicating that the water is diverting the foam filter pads due to being clogged and need a good rinse or replaced.

After the water flows through the mechanical filters, it is then pushed through to the next compartment that can either be filled with activated carbon that the filter comes with, or any other bagged media that you like.

From there, the water is then pushed through a little spout that pours the water over the wet/dry filter basket. On top of the wet/dry filter basket is a Bio-Screen, a micro weaved mesh filter pad that blocks any debris from entering the biological stages underneath. It also provides more surface area for beneficial bacteria growth.

Once the water trickles over the Bio-Screen, it falls through a basket that can be filled with whatever biological media you desire, or the Fluval C-Nodes that the filter comes with.

After passing through the 5 stages of filtration and being highly aerated by the wet/dry filter, the water then cascades gently back into the aquarium.

Designed for easy cleaningDesigned for easy cleaning #ad

Other great features of this filter are that it is easy to install, easy to perform weekly maintenance with its simple quick filter release design, and has telescopic intake tubes with an adjustable flow control valve on top.

SeaChem Tidal 55 large fish tank filter

The Seachem Tidal 55 power filter has some unique features that set it apart from other HOB filters. The only filter media that it comes with is Seachem’s biological media Matrix. The rest of the large filter compartment is open to fill as you choose.

Another clever design feature of this filter is the surface skimmer in line with the intake tube. This pulls water just under the surface and removes the oil film that accumulates on the surface of the water, as well as deeper inside the aquarium.

The amount of flow coming out of either the surface skimmer or the intake tube can be adjusted with a dial on the side of the filter.

Next is the maintenance alert system that occurs when the water bypasses the filter through the back of the filter and back into the aquarium through an outlet on the side. This water then pushes the blue indicator-up, alerting you that the filter needs to be replaced.

The best feature of this filter is the self-cleaning, corrosion-resistant impeller that makes it suitable for both fresh and salt environments.

The self-priming pump then moves the water through the filter in a bottom-to-top flow, rather than the common back to front flow.

Other great features on the Seachem Tidal 55 filter are an adjustable flow control valve, a telescoping intake tube, and an optional heater clip.

Tetra Whisper EX70 Hang-On-Back filter

This filter has a multi-stage filtration system, with two easy-to-replace multi-dense carbon cartridges (size large), and two Bio-Scrubber filters that never need replacing.

Bio-ScrubberBio-Scrubber #ad

The Whisper filter cartridge consists of a course floss pad, a carbon foam pad, and a multi-dense floss pad. Which is all housed in a rounded edge frame that makes replacing quick and mess-free.

The Bio-Scrubber filter is designed to stay clog-free and provide ample surface area for beneficial bacteria growth, helping remove ammonia and nitrites.

The Tetra Whisper EX70 is rated for aquariums up to 70-gallons, with a max flow rate of 340gph. Other sizes are also available for choice.

Hygger hang-on power filter with surface skimmer

The Hygger power filter, with a max flow rate of 158 GPH, is suitable for aquariums from 20 to 30 gallons.

It has a 3-stage filtration setup with three compartments, one filled with a sponge filter, another filled with activated carbon pellets, and the last one is filled with bio-balls. Each compartment is easy to access and clean.

This filter also has a surface skimmer and a telescoping intake tube that can be adjusted to different depths. As well as an adjustable flow control valve.

Basic HOB filter design


Every major aquarium supply company has its version of a HOB filter, all having their unique features and range in price. Understanding the fundamentals behind how and why a HOB filter works, will make it easier for you to choose the right one that suits your aquarium needs.

There are a few basic design components that all HOB filters come equipped with; the filter box, a water pump, water intake tubes, and filter media.

Filter box – A simple (partially transparent) plastic box that hangs over the edge of the aquarium. The space inside the filter box is to house all the filter media and hold the water that is filtering through.

Water pump – Usually attached to the bottom of the filter box or the water intake, depending on the brand. Most come with a magnetic impeller inside. Without going too deep into physics, the magnetic current created when power is supplied to the pump causes the impeller to spin and moves the water.

Water intake tube – The main purpose of these tubes is to direct the water suction deep down into the aquarium, allowing for better water filtration and limits the intake flow area to a smaller space.

Filter media – These typically come in easy-to-replace filter cartridges, like foam pads (mechanical), ceramic beads or highly porous media (biological), and either a carbon foam pad (mechanical/chemical) or activated charcoal bag (chemical).

How does a HOB filter work?


A HOB filter works simply by using a recirculating water pump that pulls in the water from your aquarium, then pushes the water through various filter media, and back into the aquarium.

Let’s take a deeper dive into how it filters your aquarium water step by step.

Step 1 – The powered pump creates a magnetic current that causes the impeller to spin and moves the water through centrifugal force.

Step 2 – This force pulls water up through the intake tubes, through the pump.

Step 3 – The pump then pushes the water at an increased pressure through the filter media.

Step 4 – The filtered water is then cascaded back into the aquarium.

As you can see, it is a pretty simple, yet highly effective way to filter your aquarium water. Most all aquarium filters will be designed this way, with a few individual modifications that brands give them to increase their efficiency and filtration capacity.

How to choose the right HOB filter?

When searching for the right HOB filter for your aquarium setup there are a few things to consider first.

1. Large capacity

Getting a filter that is adequate for your aquarium size is very important. If you are using a filter that is too small for your aquarium, you run the risk of under filtering your aquarium as well as fish health problems. A smaller filter will need regular maintenance to prevent the media inside from being clogged, too.

2. Flow rate

If the flow rate of the filter is too low, your aquarium will be under filtered; and vice versa, a too strong filter can stress and kill the fish. A good aquarium filter will turn over the volume of the aquarium at least 3 to 4 times in an hour. For example, a 10-gallon aquarium would need a filter that features a flow rate of 30-40 GPH (Gallon Per Hour) or higher.

The flow rate required for your aquarium depends on what kind of fish, or invertebrates you are keeping. An adjustable flow control valve is the easiest way to fine-tune the flow to fit your needs. Most HOB filters come with this capability.

3. Media type

There are three types of filter media. They are divided into three types of filtration (mechanical, biological, and chemical) based on which aquarium wastes they deal with (more here). Ideally, the filter you choose should include all three types of filtration.

Most HOB filters come with at least two out of the three filter media types. The most common is the sponge filter, which provides mechanical filtration and (limited) biological filtration. Some HOB filters take it a step further by adding in chemical filtration with either a sponge filter dusted with activated carbon or a bag of activated carbon.

A large filter allows you to add some more filter media of your choice. I preferably like to add some ceramic rings and other highly porous media in addition to the sponges that come with my HOB filters for better biological filtration.

How to set up a HOB filter?

All filters come with the filter media or cartridge suited for the filter when purchasing new. There is usually some assembly needed to get it running, but a lot of brands have them almost completely setup right out of the box.

Helpful steps to ensure a successful HOB filter setup.

Step 1 – Remove all filter components from the box.

Step 2 – Take apart the filter completely, including the pump and impeller, and give everything a good rinse. This will help you understand how the filter parts work together. Plus, knowing how to remove the pump and access the impeller will save you down the road.

Step 3 – Rinse all filter media with tap water. This will ensure that any leftover dust from manufacturing is removed before installing the filter on your aquarium.

Step 4 – Put the filter back together, making sure not to forget any pieces.

Step 5 – Hang the filter on the backside of the aquarium.

Step 6 – Plug the filter into a power outlet and let it do its magic.

Note: some HOB filters are not able to prime by themselves and you have to do this work. It may be the water pump is too weak or can’t reach the water to have the first water flow through to prime itself. It is so easy to prime a HOB filter, just take a cup and fill the filter with aquarium water before plugging it in.

Frequently Asked Questions

What media to put in a power filter?

All HOB filter brands recommend using the media that the filter comes with, but you can use any media that you like best. Just know that if you overfill the filter compartment you can run into flow issues, which affects the media’s ability to filter properly.

What about media order?

The order you place the media inside your new HOB filter depends on which filter you choose and how that filter’s specific water flow pattern. Some filters push water bottom-to-top, some back-to-front, and some combine both.

Order of media as the water flows:

  1. Mechanical filter – Foam or floss pad
  2. Chemical filter – Activated carbon bag or carbon-dusted foam pad
  3. Biological filter – Ceramic media or high surface area material

Setting your media up this way ensures that no debris or harmful chemicals get into the biological filter, and will keep your beneficial bacteria happy and healthy.

Why is the HOB filter is not working?

Is the filter plugged in? If it isn’t a self-priming filter, Is there water in the filter box? Is the water level of the aquarium too low? Have you checked the pump and impeller for damage or debris?

If you’ve gone through all these questions and the filter is still not working, the best thing to do is reach out to the manufacturer to see if they have a solution for you.

Why is the filter overflowing?

If you are noticing your filter is overflowing or bypassing the filter media, then chances are the filter pads are clogged with debris. This can easily be remedied by either rinsing the filter pad or replacing it completely.

Pro tip: If you are noticing that your filter is getting clogged way too often, this is a good indicator that your filtration setup is not adequate for your aquarium setup.

What is the best location to place a HOB filter?

You can place the HOB filter anywhere you’d like. The main thing to keep in mind when placing your HOB filter is to try to prevent water current dead spots. This can sometimes happen when there is not enough water flow in the entire aquarium.

For best flow, place the filter on the back centered in the middle and pushing the water toward the front of the aquarium. This way the water is diverted to both sides of the aquarium, rather than one side or the other.

Can you use a HOB filter for a planted aquarium?

Most HOB filters will work great on a planted aquarium. If you are injecting CO2 or adding any form of CO2, then increase the water level to avoid too much surface agitation that can cause great CO2 loss.

Can you use a HOB filter for saltwater?

For smaller or nano saltwater aquariums, a HOB filter might work alright for you. You’ll probably end up making a lot of modifications as you learn more, which a lot of aquarists do.

If you are keeping a large or heavy bio-load saltwater aquarium, then you should be looking at a sump filtration setup, or at the very least a canister filter. A HOB filter would be a waste of money.

How often to clean a HOB filter?

Once a week: Rinse mechanical and chemical filter media in dechlorinated water

Once a month: Completely un-assemble the filter, including the pump and impeller, and wipe clean with a soap-free scrub pad, every nook, and cranny.

Pro tip: Always rinse your biological filter media in discarded aquarium water, during a water change. This water is safe for helpful bacteria colonizing on the filter media. This will ensure that your aquarium won’t experience a cycle crash.

How to improve/modify an aquarium filter?

There is always room for modification no matter what HOB filter you choose. You are not obligated to use the filter cartridges that are provided by the manufacturer. Buying filter media in bulk is a great way to cut costs and improve filtration.

Using a pre-filter on the intake tube will protect small fish and fry from being sucked into the filter. It will prolong the life of the filter pump and will help reduce noise. However, you will sacrifice the high flow rate.

Adding some sort of ceramic biological media to your HOB filter is also really beneficial for your aquarium. It also will lessen the effect of bacteria loss when the filter pads are replaced.

Does a HOB filter provide oxygen?

Yes, HOB filters help increase dissolved oxygen in the water. This happens when the water is water falling back into the aquarium. HOB filters that use a wet/dry filter method will add significantly more dissolved oxygen than a HOB filter that doesn’t.

How to prime a HOB filter?

If your filter doesn’t prime by itself, before you plug in your new filter you must first prime the pump. Take a cup with some of the aquarium water and fill the filter. Then go ahead and plug it in. The pump will start moving the water and will create a siphon to get it recirculating.

Anytime power is lost to the filter, you will want to make sure that the filter is primed before it starts again. If the pump runs dry, you risk the chance of burning out the pump.

HOB filter compared to other filters

Canister filter – These are considered to be a step up from HOB filters, providing a little more versatility and complexity. Canister filters also fit all styles of aquariums, whereas HOB filters have their limits.

Sponge filter – If you are raising baby fish or shrimp (with frequent water changes), or anything that requires a really low flow, then a sponge filter (with additional biological filtration) would be the better choice over a HOB filter.

Internal filter – HOB filters are about the same as internal filters. They are all called power filters; however, externals are placed out of the water and save you some space inside the aquarium.

Under-gravel filter – power filters are no-doubt better than under-gravel filters. They are easier to set up and maintain. You can custom them in so many ways as you want to have the most efficient filtration system.

We enjoy keeping fish, and have for many years. We are trying to promote the hobby as much as possible. We want to see many others succeed in their fish keeping efforts and are committed to sharing our knowledge when we can.

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