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10 Best HOB (Hang on Back) Filters in 2020 – Buying Guide and Reviews

One of the few essential items you need to set up a healthy aquarium is a filter.

Hang on back filters (more commonly called HOB filters by fish keepers) are popular among beginner and advanced aquarists alike, as they’re easy to use and don’t take up room inside the tank.

But, if you’re not well-versed in all things HOB, you’d probably like to learn more about these filters, why they’re recommended and if interested which you should buy.

10 of the best hob filters written beside a heavily planted tank with fishIn this article, you will learn exactly what a HOB filter is, what to look for when choosing the right one for your needs, how to set one up, and finally recommendations for the best 10 on the market today.

Let’s get to it!

At a Glance: Our Top Picks for Best Hob Filter in 2020

Note: The links above take you to more information, current prices and customer reviews on Amazon.

Best HOB Filter – Product Roundup and Mini Reviews

Now for the moment of truth: below you’ll find our top 10 choices for best HOB filter.

AquaClear 70 Power Filter

AquaClear, Fish Tank Filter, 40 to 70 Gallons, 110v, A615A1

The AquaClear 70 Power Filter is one of the best models out there. Thanks to its refiltration system, you can control the flow rate without compromising the power of the filtration, which is perfect for fish that like still waters. Its unique multi-stage filtration method allows for up to six times more filtration media than other filters of comparable size.

Suit Aquarium Size

This HOB is designed for tanks of between 40 and 70 gallons. The maximum flow rate is 300gph, but it can be turned down to as low as 100gph — and doing so won’t make it less effective.

Filtration Type and Media

The AquaClear 70 has a multi-stage filtration system which provides all three types of filtration: mechanical, biological, and chemical.

The bottom layer of this three-layer system is the AquaClear Foam Insert, which helps remove debris and provides optimal water distribution patterns, so the rest of the filter can perform as efficiently as possible.

It also provides biological filtration thanks to the porous structure of foam, which offers surfaces for friendly bacteria.

The middle layer consists of premium research-grade activated carbon, which absorbs chemicals from the water.

The top layer features an AquaClear BioMax Insert, which contains BioMax ceramic rings. These filter out impurities, but also have a complex pore system that allows for a buildup of beneficial bacteria.

Filter media is included with the AquaClear 70, but you can also buy it separately, for when it needs to be replaced.

Maintenance Requirements

The AquaClear Foam Filter Insert must be replaced every two months, the activated carbon every month, and the AquaClear BioMax Insert every three months.

AquaClear recommends you take the filter apart and clean in every two weeks, but such regular cleaning probably isn’t necessary unless you’re experiencing issues with algae buildup.

Other Factors to Consider

Thanks to the AquaClear 70’s energy efficiency, it’s inexpensive to run, which is even more important when you run multiple aquariums, as it all adds up.

Since this filter comes with a lifetime guarantee, you can have it repaired or replaced should anything go wrong.

What’s more, it’s extremely quick and easy to install on any tank that has an edge or lip that’s under one-inch thick.

Overall, we rate this HOB filter highly. It’s highly durable and cleans water efficiently.

What We Like

  • The flow rate is adjustable without sacrificing filter effectiveness
  • Provides all three types of filtration media
  • Easy to install
  • Features a highly-effective multi-stage filtration system
  • Runs quietly most of the time

What We Don’t Like

  • Can sometimes vibrate, which isn’t necessarily loud but can be annoying
  • Some users report issues with leakage

The AquaClear 70 does an excellent job for an extremely reasonable price. It has some outstanding features, which other comparable filters lack, such as its re-filtration system.


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Fluval C4 Power Filter

Fluval C4 Power Filter

You can trust the Fluval C4, as it’s a sturdy filter that comes from a respected name in the world of aquatics. Its effective five-stage filtration system keeps your tank’s water healthy and clear. It also offers a range of handy extra features, such as the cleaning indicator that tells you when to change the polyfoam.

Suit Aquarium Size

The Fluval C4 is designed for aquariums of between 40 and 70 gallons, but you can find other filters in the Fluval C range that fit smaller tanks. The C4 has a flow rate of 264gph.

Filtration Type and Media

The five-stage filtration systems provide biological, chemical, and mechanical filtration.

Stages one and two provide mechanical filtration, removing particles and debris from the water. The first stage is the porous foam of the polyfoam pad, which traps large particles. The second stage is the polyfoam pad’s dense polyester, which captures fine debris.

Stage three is chemical filtration. The 100% premium research grade carbon insert removes chemical impurities from the water, as well as unwanted odors and discoloration.

Stages four and five offer biological filtration. Stage four is the bio-screen, which removes debris from the water before it drips into stage five, the C-nodes. The C-nodes is a complex pore system that houses beneficial bacteria important for the health of your who tank’s ecosystem.

Your new Fluval C4 comes with all filtration media included.

Maintenance Requirements

Like all HOB filters, a small amount of maintenance is required to keep the Fluval C4 in good shape.

You need to clean the motor, tubes, and other parts once every three months. Plus, once a year, you must clean the impeller cover and replace the motor O-ring.

Apart from that, all you need to do is change the filtration media.

You need to replace the polyfoam every three to six weeks (or when the cleaning indicator comes on), the activated carbon insert every two to four weeks, and the bio-screen every two to three months. Once every six months, replace half of the biological C-nodes but never replace them all at once or you’ll lose all the friendly bacteria.

Other Factors to Consider

The Fluval C4’s patented re-filtration system means you can turn down the flow rate of the water without making the filter less effective. This is ideal if you keep fish that like their water still.

What We Like

  • Each stage of the filtration system is self-contained, so you can remove one stage with disturbing the others
  • It’s possible to customize the filtration media if you don’t want or need all three types of filtration
  • Tube intake height is easy to adjust and doesn’t require adding extra segments of tubes
  • Users report this filter running for years without issue

What We Don’t Like

  • It’s not the quietest model out there
  • The C4 can struggle to restart after it’s been stopped, so power outages may be a problem

Although it has a few downsides, we think this is an excellent HOB filter overall. What’s more, it’s extremely reasonably priced considering the quality.


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Seachem Tidal Filter by Sicce 55 Gallon

SeaChem Large Aquarium Fish Tank Filter, Tidal 55 Gallon (200 Liters) by Sicce

The Seachem Tidal Filter is a well-constructed model that’s designed for both saltwater and freshwater use, thanks to its self-cleaning, non-corrosive impeller.

The self-priming pump makes it extremely to setup, and to restart after cleaning, maintenance, or a power outage.

Suit Aquarium Size

This Seachem Tidal Filter 55 Gallon is — as the name suggests — suitable for tanks of up to 55 gallons. Its flow rate is 250gpm.

Filtration Type and Media

The filter basket of the Seachem has a large capacity, designed to hold any filtration media you choose, which is ideal for experienced fish keepers who know precisely what kind of filtration they require.

However, it can be confusing for beginners who would prefer to buy a HOB filter that contains all the media they need, ready to go.

That said, it does come with Seachem’s Matrix bio-media, which provides biological filtration to control ammonia, nitrite, and nitrate. If you choose to use any other kinds of filtration media, you’ll have to buy separately.

Maintenance Requirements

Good news for busy aquarists, the Seachem Tidal Filter is very low-maintenance, even compared to other HOBs.

The impeller is self-cleaning, so you don’t have to worry about that, but the rest of it will need occasional cleaning. This filter features a maintenance alert device, which indicated when it’s starting to clog and needs to be cleaned.

You’ll also need to change whatever filtration media you choose to use.

Other Factors to Consider

The pump on the Seachem Tidal is highly-insulated and therefore silent, so it’s perfect if the noise of HOB filters puts you off.

It also has a double-intake system, featuring a surface skimmer to capture water from just under the surface, where you can get a build-up of excreted fish oils, as well as a standard underwater intake.

What We Like

  • The telescoping underwater intake is a breeze to adjust and can take water from anywhere in the tank
  • You can easily adjust the flow of the pump using the dial on the front if you need less water flow
  • The bottom-to-top flow of water through the basket ensures that water goes through all the filtration media inside
  • Since the Seachem consumes very little power, it’s eco-friendly and could save money on your energy bills

What We Don’t Like

  • The all-black body makes it difficult to see if there’s an algae build-up in the tubes or chamber
  • Doesn’t fit well on tanks with larger lips

Although it’s not as popular or well-known as some other HOB filters, the Seachem Tidal is exceptionally sturdy and works well. Plus, it offers a range of handy features, such as the self-cleaning impeller and the surface skimmer.


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Marineland Penguin Power Filter

If you want a decent HOB on a budget, look no further than the Marineland Penguin Power Filter.

Despite its highly affordable price, it has good reviews is a bestseller at many online stores. This is a great filter that’s easy to use and maintain.

Suit Aquarium Size

The Marineland Penguin we looked at in depth is designed for tanks of up to 70 gallons and can turn over 350gph. However, three smaller models are available for tanks of up to 20, 30, and 50 gallons. They turn over 100gph, 150gph, and 200gph, respectively.

Filtration Type and Media

The Penguin Power offers three-stage filtration, featuring mechanical, chemical, and biological media.

The first stage features the Penguin Rite-Size Filter Cartridge, which removes dirt and debris from the water.

The second stage is the Black Diamond Premium Activated Carbon, which removes odors and chemical impurities from the water.

The third stage is Marineland’s patented Bio-Wheel, which harbors beneficial bacteria that eliminate toxic ammonia and nitrite.

This filter comes with the bio-wheel and other media.

Maintenance Requirements

Expect to do about the same amount of maintenance on the Marineland Penguin as you would on any other model. The cartridges need to be cleaned or replaced about once a month. At the same time, you should give the tubes and the basket a good scrub, too.

Other Factors to Consider

The two-piece vented covers are designed to reduce noise. However, noise levels seem to be subjective, as some users find this filter very quiet, whereas others complain it’s too noisy.

These work equally well in both saltwater and freshwater aquariums.

What We Like

  • This is a highly functional unit with good reviews that comes at a very reasonable price
  • No need to shut the filter down to replace cartridges
  • Lots of room in the basket for extra filtration media, if required

What We Don’t Like

  • Can’t control the flow rate
  • Not as sturdy as some more expensive HOB filters

It might not be the fanciest filter with all the bells and whistles, but we can’t get over how much value for money the Marineland Penguin Power provides.


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Marineland Emperor 400 Pro Series Bio-wheel

Marineland Emperor 400 Pro Series Bio-wheel Power Filter - Up to 80 gallon, Rite Size 'E'

The Marineland Emperor 400 is a step up from its Penguin models. The two-pump design provides excellent filtration and flow, while the double cartridge capacity keeps water crystal clear. Thanks to the sturdy design, this filter should stand the test of time.

Suit Aquarium Size

With a flow rate of 400gph, the Marineland Emperor 400 is designed to suit tanks of up to 80 gallons in capacity.

Filtration Type and Media

This HOB filter provides mechanical, biological, and chemical filtration.

The Emperor 400’s Rite-Size E Cartridges provide both mechanical and chemical filtration: the double thick poly-fiber trapping debris and the Black Diamond Premium Activated Carbon filters out chemical impurities.

It also comes with a bio-wheel, which hosts beneficial bacteria, providing biological filtration.

There’s also a spot to fit one of Marineland’s refillable media containers, which can be filled with a filtration media of your choice.

The filter comes complete with two Rite-Size E Cartridges, two 4oz refillable media containers, and two spray bar-driven bio-wheels.

Maintenance Requirements

It’s not hard to maintain the Marineland Emperor 400. Simply clean the unit and change the cartridges monthly. You may also need to clean and unclog the impeller occasionally. You shouldn’t, however, replace the bio-wheel unless it breaks, as doing so will kill the friendly bacteria living on it.

Other Factors to Consider

The extra-large chamber means you can fit plenty of filtration media, which is useful if your tank’s inhabitants produce a lot of waste.

This certainly isn’t the quietest model on the market, so bear that in mind if your tank is in your bedroom or living room.

What We Like

  • Easy to customize by adding more filtration media in the refillable containers
  • The large bio-wheel provides excellent biological filtration
  • Spare parts are easy to get hold of should you need to repair this filter down the line

What We Don’t Like

  • The Emperor 400 is relatively loud
  • Being black all over means it’s hard to tell if there’s a buildup of algae inside

The Marineland Emperor 400 is proof that you can get a highly-durable, feature-rich HOB filter without it costing the Earth.


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Tetra Whisper Power Filter

Tetra Whisper Power Filter 60 Gallons, Quiet 3-Stage aquarium Filtration, Model Number: 46798257752

While it might not be as flashy as some alternatives, the Tetra Whisper Power Filter is a solid, popular model that gets the job done at an affordable price. It’s a simple model that features cartridges, as well as biological filtration.

Suit Aquarium Size

The model we’re looking at is suitable for tanks of up to 60 gallons and turns over 330gph. You can, however, find other filters in Tetra’s Whisper range designed to suit smaller tanks, between 10 and 40 gallons.

Filtration Type and Media

The Tetra Whisper Power Filter provides three-in-one filtration—mechanical, chemical, and biological.

The Bio-Bag cartridge offers both mechanical and chemical filtration. Mechanical filtration comes from the bag’s dual-sided mesh, which removes dirt and debris from the water. Chemical filtration comes from the activated charcoal inside the cartridge, which helps to remove chemical impurities.

It can also hold one of Tetra’s Bio-Foam pads, which provide biological filtration by housing colonies of good bacteria that filter out nitrites and ammonia.

While the Whisper comes with a couple of Bio-Bags included, it doesn’t come with a Bio-Foam pad included.

Maintenance Requirements

Just like other HOB filters, the Tetra Whisper Power doesn’t need a lot of maintenance. To keep it in good shape, we’d recommend you take it apart and clean it once a month. You’ll also need to change the Bio-Bag cartridges every three to four weeks.

If you choose to use biological media, don’t replace, clean it, or let it dry out. Otherwise, you’ll lose the bacteria that provide the filtration.

Other Factors to Consider

The Tetra Whisper Power is supposed to run quietly. While this is usually the case, some users report their filters being noisy. However, a noisy filter is usually due to some error, so if it runs loudly, you should check it’s correctly installed.

All in all, this is a reasonably durable filter, though it’s not as long-lasting as some more expensive models.

What We Like

  • The filter bags allow you to add other kinds of media, should you choose to
  • Runs very quietly, as long as the impeller is installed correctly in its housing
  • Straightforward to install
  • Offers great value for money

What We Don’t Like

  • Intake tube could be longer or come with an extender
  • The Bio-Bags don’t always contain enough carbon

If you’re looking for an affordable option, the Whisper isn’t a bad choice. Though it’s certainly not perfect, we can’t fault it for the price. Tempted?


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Aqueon Quietflow 50 Filter

Aqueon QuietFlow 50 Power Filter 250GPH, Plus 3-Replacement Filter Cartridges

The Aqueon QuietFlow 50 stands out for its impressive range of features, including its self-priming pump and LED indicator that tells you when it’s time to change filter cartridges.

The problem is, it doesn’t perform quite as well overall as some of its competitors with similar features. Even so, it’s still a contender in our top 10 and is very affordable, considering what it can do.

Suit Aquarium Size

The QuietFlow 50 is rated for tanks of up to 50 gallons and can turn over 250 gallons per hours. You can buy other filters in the QuietFlow range for both larger and smaller aquariums.

Filtration Type and Media

This filter features a feature five-stage filtration system, utilizing mechanical, chemical, and biological media, plus a specialty pad.

The first stage provides mechanical filtration using floss that removes particles and debris from the water.

The second stage is chemical filtration—activated carbon removes harmful chemicals and toxins, as well as getting rid of odors and discoloration.

The third stage features Aqueon’s Patented Bio-Holster. This provides biological filtration, which removes ammonia and nitrites from the water.

The fourth stage is a diffuser grid, which removes any remaining toxins and adds extra oxygen to the water, which benefits fish.

The fifth stage gives you the option to add a specialty pad, which can contain ammonia reducer, phosphate remover, or more activated carbon.

While it comes with all standard filtration media, you’ll need to buy specialty filter pads separately, if required.

Maintenance Requirements

Aqueon’s QuietFlow 50 doesn’t have any maintenance requirements beyond those of any other HOB filters—regular cleaning and changing of cartridges is all it requires.

Other Factors to Consider

This is a very quiet filter, thanks to the internal pump design and the diffuser grid, which is a huge plus for many fish keepers.

While the majority of users love this filter, a substantial number of people have complaints about unwanted vibrations, breakdowns, and it simply not working straight out of the box. This leads us to believe it’s not the most reliable or durable model out there, even if it works perfectly most of the time.

What We Like

  • The self-priming feature means it can start up automatically after you’ve shut it down to clean or there’s been a loss of power
  • The diffuser grid reduces splashing, which makes this model quieter
  • Included filter cartridges contain more activated carbon than other brands
  • The LED indicator light tells you when to change filters

What We Don’t Like

  • The Bio-Holster may not provide adequate biological filtration for some tanks
  • Not the most reliable option

While you can find better HOB filters out there, this is still a good choice, particularly if you want features like self-priming without a considerable price tag.


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Penn Plax Cascade Hang-on Aquarium Filter

Penn Plax Cascade Hang-on Aquarium Filter With Quad Filtration System Cleans Up To 50 Gallon Tank

Durable, quiet, and with a large enough chamber to customize with your own filtration media, the Penn Plax Cascade Hang-on Aquarium Filter is an excellent choice for fish keepers of all experience levels.

It features a range of intuitive and easy to use features, such as the adjustable intake tube and the self-leveling system.

Suit Aquarium Size

The Cascade 200 model that we’re looking at in-depth has a flow rate of 185gph and is designed for tanks between 35 and 55 gallons. That said, Pen Pax recommends that you size up to a larger filter if your tank is especially well-stocked or holds creatures that produce a lot of waste, such as turtles or goldfish.

Filtration Type and Media

The Penn Plax Cascade offers mechanical, chemical, and biological filtration in a four-step process.

Mechanical filtration comes from the polyfiber floss cartridge, which traps dirt and debris.

Chemical filtration is down to the activated carbon cartridge, which removes any harmful chemicals and other contaminants in the water, as well as dealing with odors and discoloration.

Biological filtration is thanks to the internal bio-sponge, which provides a place for beneficial bacteria to grow, removing ammonia and nitrites from the water.

Secondary biological filtration comes from the external Bio-Falls wet/dry biological booster. This provides a place for more friendly bacteria to grow, plus it increases water oxygenation.

All media is included with the Penn Plax Cascade.

Maintenance Requirements

There’s no need to replace the bio-sponge or the Bio-balls unless they wear out, so all you need to do to keep this filter running is clean it and replace the floss and carbon cartridges monthly.

Other Factors to Consider

This filter runs extremely quietly. In fact, it’s almost silent and is one of the quietest models we’ve come across.

Since the Cascade comes with a three-year warranty, you can rest assured that Penn Plax will take care of any problems that arise in this time.

What We Like

  • It’s ready to go out of the box and installation is extremely straightforward
  • The flow rate is adjustable, which is good for feeding times or fish that don’t appreciate currents in the water
  • You can easily adjust the intake tube without adding extra segments

What We Don’t Like

  • Included media could be better
  • Some users find it gets louder as it ages

If you’re looking for a quiet filter at an affordable price, look no further than the Penn Plax Cascade. It might not come from as well-known a brand as some, but it does the job well.


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EHEIM Liberty 200 Hang on Filter

EHEIM Liberty 200 Hang On Filter for up to 50 US Gallons

It might look utilitarian, but the EHEIM Liberty 200 Hang On Filter works well and comes at an affordable price. It’s extremely simple to use and is designed to be functional. It’s very straightforward to control the flow output, plus the impeller and inlet pipe are easy to remove and replace for cleaning.

Suit Aquarium Size

The EHEIM Liberty 200 has a flow rate of around 200gph and is designed for tanks of up to 50 gallons. However, 50 gallons is the absolute maximum capacity, and it may not be powerful enough for heavily populated 50-gallon tanks.

Filtration Type and Media

A combination of filter cartridges and a bio-sponge provide mechanical, biological, and chemical filtration.

A carbonized phenol-free cellular foam pad cartridge offers both chemical and mechanical filtration, while a large sponge filter provides a home for beneficial bacteria, which will remove ammonia and nitrites, once a colony has built up.

The EHEIM Liberty comes with filtration media included in the price.

Maintenance Requirements

Other than monthly cleaning and changing of the filter cartridges, the EHEIM Liberty requires very little maintenance. You may sometimes need to clean the impeller, but it’s simple to remove from the motor, making the process straightforward.

Other Factors to Consider

The EHEIM Liberty 200 is extremely quiet—in fact, some users would describe it as silent.

While it comes with EHEIM’s official media included, you can choose to use other filtration media, if you prefer, or add extra alongside of the included media.

What We Like

  • The lid doubles up as a tray to carry old filters, so you don’t drip water all over the place when throwing them out
  • Sturdy and built to last
  • Has the ease of the user in mind—everything’s simple to use and adjust

What We Don’t Like

  • Not the most attractive looking option
  • Filter media isn’t often available in stores, so you’ll have to buy online

Overall, we think the EHEIM Liberty is a great filter. While it’s not flashy, it offers all the features you need from a HOB, without any unnecessary extras.


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Marina Power Filter

Marina S10 Power Filter

Last, but not least, is the Marina Power Filter. With almost five stars on Amazon, this is a practical and reliable choice for small tanks. With a self-priming function and easily adjustable flow control, this user-friendly HOB is an excellent option.

Suit Aquarium Size

We’re focusing on the Slim S10 model, which is suitable for tanks of up to 10 gallons and has a flow rate of 50gph. However, you can also buy Slim S15 and Slim S20 models in the same range, which suit aquariums with capacities of up to 15 and 20 gallons, respectively.

Filtration Type and Media

The Marina S10 claims to provide mechanical, chemical, and biological filtration. However, the effectiveness of the biological filtration is questionable.

This filter comes with two cartridges: a Bio-Carb cartridge for chemical filtration and a Bio-Clear cartridge for mechanical filtration. The Ceramitek in both cartridges is designed to promote biological filtration.

However, since you must remove and replace the cartridges every three to four weeks, when you do so you’re getting rid of the beneficial bacteria. It’s recommended you only replace one cartridge at a time, so you don’t kill off all the bacteria at once, but it’s still not ideal.

You can, however, choose to fill the chamber with your own choice of media, if preferred.

Maintenance Requirements

Maintenance on the Marina Slim S10 in minimal. You need to replace the cartridges fairly regularly, but they’re extremely easy to slot in and out of the chamber, which saves time and effort. You’ll also need to clean the filter monthly, or when it appears dirty.

Other Factors to Consider

The self-priming feature means that you don’t have to manually refill the filter with aquarium water every time you need to stop and restart it.

Good news for lovers of peace and quiet—the Slim S10 makes hardly any noise at all.

What We Like

  • The slimline design means you don’t need a lot of space between your aquarium and the wall
  • It’s easy to customize this filter with your own media
  • The flow rate is adjustable

What We Don’t Like

  • The biological filtration media isn’t ideal
  • Only suitable for small aquariums

Looking for a quiet filter for a small aquarium that won’t put a dent in your bank balance? Well, the Marina Slim S10 is the one for you. Want to take a closer look?


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What is a HOB Filter? How Does a Hob Filter Work?

A hang on back filter is a relatively bulky filtration device that hangs off the rear wall of your aquarium (as you can probably guess from the name).

Although HOBs are big, they don’t take up any room in the aquarium, so its inhabitants have more space to swim around.

A HOB does its job by drawing water out of the tank through a lift tube and into the filter. Once inside, the water is pushed through a series of channels where it goes through the filter media, cleaning the water. Then the clean water flows black into the tank over a spillway or overflow.

Depending on the model you choose, a HOB may use either a chemical, biological, or mechanical filtration media — or any combination of the three.

HOB vs. Canister Filter

Canister filters are another favorite variety of filter. As such, many fish keepers wonder whether they should select a HOB or a canister type. Of course, you’ll find pros and cons to each, so it’s not a simple decision.

Canister filters are effective with a good capacity and flow rate. Due to their large size, you can fit a lot of media inside. That said, they can be awkward to install and to clean.

Hang on back filters have a good flow rate and capacity, are extremely easy to install, don’t take up space in the tank, and are a breeze to clean.

Some models don’t have as much space for different filter media, but this shouldn’t be a problem unless you keep fish that need pristine water conditions and/or produce a lot of waste.

What You Need to Know about HOB Filters

If you’re going to use a HOB in your aquarium, you should learn a little about them and how they work. Here’s what you need to know about hang on back filters.

  • Filtration: The filter cartridges inside a HOB provide either biological, mechanical, or chemical filtration (or a combination of all three). Some models have a bio wheel, which promotes the growth of beneficial bacteria in your tank — otherwise, the biological filter will remove it all. Don’t clean the bio wheel or let it dry, as this will kill the friendly bacteria.
  • The Motor: A HOB filter’s motor is what pulls water into the tank and through the filter. Newer models generally have built-in motors, whereas older models have detachable motors. The benefit of built-in motors is that you don’t need to remove them and clean them. We’d recommend covering the impeller, so debris doesn’t get in.
  • Water Spouts: Depending on their size, HOB filters either feature one or two water spouts that serve to return clean water back into the tank after filtration.
  • Maintenance: One of the great things about HOB filters is they require very little maintenance. You must replace the cartridges every three to four weeks, but that’s about it. Occasionally, an algae build-up may occur inside the filter and the tube. In which case, all you need to do is give them a quick scrub.

Why Might You Want a HOB Filter?

Why, exactly, should you buy a HOB filter? What are their benefits? Here we examine what’s good about HOBs.

  • Since it hangs on the back of your tank, rather than inside it, it’s easy to access your HOB filter when you need to change the cartridges, or the unit needs cleaning.
  • Hang on back filters tend to be fairly inexpensive compared to other types that provide the same level of filtration, so that’s good news for your wallet.
  • Thanks to new technology, most HOB filters you buy today are very quiet, unlike their older noisier counterparts.
  • You’ll find that HOB filters have a decent capacity and provide effective
  • If you prefer your tank to be low-maintenance, note that you don’t have to do much to keep HOB filters running, other than changing the cartridges.

Factors to Consider When Choosing a Hang on Back Filter

Not all hang on back filters are the same. Some are designed for larger tanks, some have different flow rates, and some are more expensive than others. Consider the following factors before purchasing a HOB filter to make sure you choose the right one for you and your aquarium.

Aquarium Size

Your chosen HOB filter must be appropriate for the size of aquarium you have. If you use one that’s not powerful enough for the size of your tank, the water won’t get clean enough, and the aquarium’s residents will suffer.

It’s better to have a filter that’s slightly too powerful for your tank than not powerful enough. That said, an extremely powerful HOB may create too much current in the water, which many fish don’t enjoy.

Most HOB filters will list the approximate tank size (in gallons) that they’re suitable for.

The Flow Rate

Learning the flow rate of any HOB filters, you’re considering buying will help you find out if they’re appropriate for the size of your tank.

The flow rate is the amount of water a tank can filter in an hour. It’s recommended that your chosen model can turn over at least four times the capacity of your aquarium every hour. So, if you have a 50-gallon aquarium, you’ll need a filter with a minimum flow rate of 200 gallons per hour (gph).

However, this is just a guideline, and what works for one tank setup may not work for another.


HOB filters vary in price, depending on a range of factors, including the size, flow rate, manufacturer, and overall quality.

While we wouldn’t recommend opting for the very cheapest filters out there, you don’t have to spend a lot if you don’t have the money to do so. We’d recommend setting yourself a budget, so you can keep it in mind as you look at HOB filters.

The Filtration Media You’d Like to Use

Depending on the model you choose, your HOB may use any of the three main filtration media (mechanical, chemical, or biological) or a combination thereof.

Many filters are set up to use all three, though you can often pick and choose which to use. Decide which type of types of filtration media you want to use and make sure whichever hang on back filter you ultimately choose is compatible with it.

If you’re unsure what kind of filtration media you need, we’d recommend opting for all three. This is generally the best bet unless there’s a particular reason not to, but this usually is only the case with non-standard aquarium setups.

Maintenance Required

All filters require some maintenance, but the majority of HOBs need very little. Besides cleaning it now and again, and changing the filtration media, you shouldn’t have to do much to keep your filter running.

Those models without covers on the impeller generally require a little more maintenance, because the impeller will need intermittent unclogging.

Other Indirect Factors

You may find you have other factors to think about, dependent on your situation at home. If you have pets or young children at home, they could be disturbed by a noisy filter, so you’d need to look for a quiet one.

Also, consider the environment the residents of your rank enjoy. If they like still water, make sure you can adjust the output to keep water still. Conversely, you may need a very powerful filter if your fish like fast-flowing water.

Video: How To Set Up A HOB Filter

Once you select and purchase your HOB filter, you’ll need to know how to set it up. While the video below shows you how to set up the AquaClear 110, the setup process for all hang on back filters is fairly similar. Check out this video to see how it’s done.


How to Clean a HOB Filter

One of the few things you need to do to maintain your HOB is to clean it. We’d recommend doing this around once a month. Many people do it at the same time as their monthly water change. If you’re unsure how to clean your filter, simply follow these steps.

  1. Make sure tit’s unplugged and then remove it from your tank.
  2. Take off the lid and remove the cartridges or basket that holds the filter media.
  3. Clean the sponge and any biological filtration (such as ceramic disks) in some water from your aquarium. Don’t use tap water as it will kill the friendly bacteria.
  4. Replace the activated carbon (if using).
  5. Take off the intake tube and any other tubes, and clean inside with a small brush.
  6. Take the motor out and clean the impeller. Lubricate the motor and seal the gasket as you replace it.
  7. Put your filter back together and replace it on the aquarium. Fill it up with a cup of old aquarium water before you plug it back in.


Hang on Back Filter FAQ

Do you have any questions on HOB filters? We will answer them and add them to the FAQ here as we have them come in.

What Media to Use in a Hob Filter?

This will vary from model to model. Many HOB filters use a variety of media, including chemical, mechanical, and biological. The simplest models may have just one or two.

Use the media included with your filter, and consult the owner’s guide when it’s time to replace the media. Follow the link to learn more about the different types of aquarium filter media available and what they do.

How Does a Hob Filter Work?

All HOB filter models work in essentially the same way. An impeller draws water from down in the tank through an intake tube. The water passes through one or more filters before it’s returned to the tank. Mechanical filters will capture debris that you can dispose of later. Some models may also use chemical and/or biological filtration to clean the water further.

When first set up, you will likely need to prime the pump by filling the reservoir with water from the tank before turning it on. For more on HOB filters, please read this comprehensive and interesting article.

How to Make Hob Filter Quieter?

If you find your HOB filter is noisier than when first installed, it may be that it’s partially clogged or the impeller is not sitting in place properly.

Remove the impeller and intake tube and rinse them thoroughly until all debris is clear. When reinstalling, be sure the impeller is resting securely. You might also try attaching felt pads between the reservoir and the outside of the aquarium to reduce the noise from vibration.

Where to Place Hob Filter?

HOB stands for Hang On Back. Find a spot at the back of your tank that can accommodate the filter and hang it there.

Try to keep it clear of other cords or air hoses that feed into the tank. If your tank came with a hood, there is probably a spot designated for a HOB filter.


Product image credits: © Amazon.com

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Wendy Kathryn

Hi, I'm Wendy, the owner and creator of this website, an experienced fish keeper and avid student of the art since 2010. My aim is to help beginners avoid the many possible mistakes when getting started in this wonderful hobby.