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Best Hob Filters for Your Aquariums

Of all the filtration systems on the market, no style is more popular across a wide spectrum of users than the humble hang on back type known as HOB filters. There are probably more versions of this filter available than any other type too, which can present a problem for novices: How do you choose the best HOB filter for your tank?

Quick Comparisons Of The 6 Best HOB Filters

IMAGE BRAND DETAILS
tnk-table__imagePenn Plax Cascade
  • Capacity: 20 to 35-Gallons
  • Dimensions: 6.75 x 7.25 x 4.75 inches
  • Flow Output: 150 GPH
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tnk-table__imageAqueon QuietFlow LED PRO
  • Capacity: Up to 90-Gallons
  • Dimensions: 14.2 x 9.2 x 7 inches
  • Flow Output: 400 GPH
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tnk-table__imageMarineland Penguin Filter
  • Capacity: Up to 20-Gallons
  • Dimensions: 8 x 5.5 x 8 inches
  • Flow Output: 100 GPH
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tnk-table__imageTetra Whisper Power Filter
  • Capacity: 5 to 10-Gallons
  • Dimensions: 4.2 x 6 x 7.1 inches
  • Flow Output: 90 GPH
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tnk-table__imageAquaClear 50 Filter
  • Capacity: Up to 50-Gallons
  • Dimensions: 4 x 9 x 8 inches
  • Flow Output: 200 GPH
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tnk-table__imageSeachem Power Filter
  • Capacity: Up to 55-Gallons
  • Dimensions: 8.0625 x 5.5 x 7.75
  • Flow Output: 250 GPH
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Introduction To HOB Filters

HOB Filters in blue background

There was a time when fish keepers only had a handful of options for filtering their aquariums: cheap undergravel filters, midrange HOBs and expensive canister systems. When I first started keeping fish there were only two brands to choose between, and neither HOB was available for tanks under 10 or over 100-gallons.

Filter technology has come a long way since then and HOBs are now manufactured in the budget and premium ranges and for tanks of all sizes. Let’s take a look at the best hang on back filters and talk about why their popularity has skyrocketed in the last decade!

Advantages Of Hang On Back Filters

Before we dig into HOB features and talk about selecting the right model, why would you need this type of filter over the other options? Every style has its advantages, but I would argue that the benefits of HOBs make them an ideal choice for the widest number of novice and experienced aquarists:

  • HOBs are one of the easiest types of filter to install in new or existing tanks
  • HOB power filters are electrical and don’t require a separate air pump to operate
  • They come in more sizes than any other style, since they are available for tanks from 5 to 500-gallons
  • HOB design allows the filter pads, media, and motor/impeller to be accessible for routine maintenance
  • They offer 2 or 3-stages of filtration and filter pads/media allow for customization to provide the exact type of filtration your tank needs
  • The ideal style of filter for community fresh and saltwater aquariums planted tanks and reef tanks
  • Easily used as either your primary filter or as a secondary method of filtration for larger or more complicated aquatic set-ups

Features Of HOB Filters

Now that you know about their benefits, it’s time to talk about the typical HOB features. While all filters do the same job, HOBs have some unique ways of accomplishing the water-cleaning task.

Filtration Stages Allow For Customization

One advantage HOBs have is in the flexible design of the box that holds the stages of filtration: the filter pads and media. While most manufacturers sell pre-filled replacement pads with media that you can just pop in the filter, you also have the option of buying padding in bulk and cutting your own if you prefer to save money.

 

Penn Plax Cascade Hang-on Aquarium Filter with Quad Filtration System

By design, HOBs have at least 2-stages of filtration: Mechanical and Chemical. Many premium HOBs also have extra baskets or containers to hold additional types of media for targeted chemical filtration. It’s also become quite common to include a third stage for biological filtration, though the effectiveness of these stages vary.

Motors And Impellers

HOBs have an external motor that’s usually connected to the bottom of the intake side of the filter box. The motor powers an impeller inside the box which spins and pulls water up the intake tube. The magnetic impeller is directly exposed to the water moving through your filter but the motor is protected and stays dry.

One challenge with maintaining a HOB is keeping the impeller clean and free of algae, sand or other debris. Since the impeller is only connected to the motor via a magnet, it doesn’t take much build-up to prevent it from spinning. If your filter starts to make a grinding sound you may need to maintain or replace your impeller.

HOBs are usually noisier than internal and canister filters because the motor is not contained within the aquarium or filter box. You’ll likely hear a hum when the motor is running, and obviously, the impeller’s condition will alter the sound as well. One reason some aquarists avoid HOBs in bedroom tanks is due to these noise issues.

Intake And Outflow

Penn Plax Cascade HOB Filter

All HOBs have an intake attached to a tube that sits in your tank to suck up debris and move water through the filtration system. You can usually adjust the height of the intake, although for deep tanks you may need additional hard plastic tubing to extend the intake lower.

Intakes usually have a plastic screen to prevent fish from being sucked into the filter, but you may need to adjust this if you have a lot of delicate fish, shrimp or fry in your tank. I often modify HOBs with a fine sponge filter tip instead of using the plastic screen that comes with it. But this can also reduce your flow rates.

The outflow on a HOB is a bit like a waterfall feature as it pours the filtered water back into your tank. This helps oxygenate your water, but it increases the noise of the filter, especially as your water level gets lower. The outflow also increases evaporation, which can lead to hard water deposits and salt creep in marine tanks.

How To Choose The Right HOB For Your Tank

Once you’re convinced a HOB is the best choice for your tank, how do you go about researching and choosing a filter? There are four things I look for when buying my aquarium filters:

Aquarium Size

A green beautiful planted tropical freshwater aquarium with fishes

Look for a model that’s designed for your aquarium size. Most filters will have a tank size or range of sizes listed on the box to guide you, although this can be a bit subjective. It’s not a great idea to use a filter made for a different sized tank, as this may leave your tank under or over-filtered.

Flow Rate

Most brands will list the maximum flow rate or gallons per hour (GPH) cycled through the filter under the best-case scenario. Your actual flow rate will depend on the condition of your filter’s intake tip, pads, media, impeller and motor. Filled media baskets can also reduce or alter your flow rates.

While there’s debate about the ideal flow rate, I usually start with a filter that cycles all the water in my tank about four times an hour, or two for low-flow species like shrimp, Bettas and goldfish. Then I add extra filtration to the tank as needed, especially for large or planted tanks. I talk about using multiple systems below.

Sound And Noise

Since their motor is external and they sit on and not under your tank, HOBs are usually noisier than canisters to operate. The motor causes the whole box to vibrate, so loose parts or lids often rattle, especially on cheap models. There’s also the sound of your impeller and outflow to consider.

As your filter ages, it usually gets noisier. The parts sit looser and the vibrations are more obvious. Cheaper filters often require frequent impeller replacement to mask their sound and keep the water moving. HOBs may not be the best choice for an aquarium in a TV room or bedroom if you’re sensitive to noise.

Special Features

Manufacturers often advertise their HOBs as having unique or special features like adjustable flow rates, LED indicator lights for routine maintenance or to alert you that the filter pads need changing, multiple media baskets and separate biological filtration stages.

The effectiveness of these features vary by model, so I recommend doing research and talking with other users of the filter before picking your HOB. That will help you identify the filters that have features that work the way you need them to and help you avoid those with gimmicks.

Tips For Using HOB Filters

Now that you’ve got the scoop on picking out your HOB filter, let’s talk about how to get the most out of your system. Before you finally settle on your HOB model, consider:

Filter Placement

As their name suggests, HOBs are usually placed discreetly on the back of the aquarium. They are often very slim by design to fit between your tank and the wall, and they need about an inch clearance on all sides. They may also fit on the side of your tank, but it may not work with your aquarium lights, lids and hoods in the way.

It can be a challenge to fit a HOB on a rimless tank or tank that’s custom-built. Oftentimes, you’re better off going with an internal or canister system instead of trying to jury-rig a HOB filter on a non-standard tank. Most of these systems fit easily on a standard-sized rimmed aquarium, however.

No matter where you decide to place your HOB, be sure you can easily access the filter box. You don’t want to discover later that you’ve placed it in a spot you can’t easily see or reach. You should check your filter pads and clean your filter box monthly and be able to quickly access it in an emergency.

Why You Might Need More Than One Filter

The flow rate of your filter does matter, and I talk about this above, but no matter how powerful your filter is it won’t be able to pull debris in from all areas of a large tank. Plants and decorations get in the way, so a heavily planted or decorated tank may need additional filtration systems to keep them clean regardless of flow ratings.

A green beautiful planted tropical fish tank.

The location of your HOB matters more in a large or long tank than in a small or tall one. In a small tank, the intake is best located near the center-rear portion so it can pull in debris from both ends. In longer tanks, you may need multiple filters with intakes in several locations along the rear to keep it clean.

Replacement Filter Pads And Media

While you can usually buy replacement pads pre-filled with media, it may be cheaper and more effective to cut your own pads and fill the baskets with your choice of bulk media instead. Most brands use a tablespoon or two of media at most in their premade pads, which limits their chemical filtration.

This also allows you to choose a finer filtering pad for more water-polishing power, although these types clog faster and may reduce your flow rate. Still, a big reason I love HOB filters is the ability to easily customize their stages!

Using HOBs In Saltwater Aquariums

You can use hang on back filters for saltwater tanks, although it’s more common to use them as secondary filtration systems in marine aquariums rather than the primary.  Fish-only tanks usually do well with a HOB filter but tanks with coral and live rocks often need the higher filtration capacity offered by canister systems.

Coral Saltwater reef aquarium tank

You’ll often see reef tanks with both HOB and canister filters running, and large reef tanks may also have a sump system. So if you’re asking “what kind of filtration do I need for my 15-gallon reef tank” the answer would be to choose a canister system as a primary and add a HOB if you need more filtration power.

Best Hang On Back Filters: Product Reviews

It’s never easy to make a short list of HOB filters to review, simply because there are so many brands and models! While I’ve chosen these as the best representatives of the modern HOB, this is by no means a definitive or exhaustive list of filters.

Most of these filters are also available in other sizes, so if the model I review doesn’t fit the tank you own, check and see if they make that model in a size compatible with your aquarium. The features may vary among the different sizes, so you’ll have to research them.

1. Penn Plax Cascade HOB Filter With Quad Filtration System

Penn Plax Cascade Hang-on Aquarium Filter with Quad Filtration System
  • Capacity: 20 to 35-Gallons
  • Dimensions: 6.75 x 7.25 x 4.75 inches
  • Flow Output: 150 GPH
Check The Price

 

If you’re looking for a basic 3-stage HOB at a budget price, the Penn Plax Cascade with Quad filtration could be the pick for you. This is a straightforward filter that has some interesting premium features. The large media box holds your replaceable filter pads and a coarse, permanent pad for biological filtration.

The outflow is where the Penn Plax gets interesting. Instead of just flowing back into your tank, this stage separates the flow to increase the water oxygenation and improve the function of the biological stage. That’s why it’s called a quad filter. This design also increases evaporation and may increase build-up on your tank.

Benefits Disadvantages
  • Basic 3-stage filter with extra-oxygenating outflow
  • Has an easily adjustable flow rate knob
  • Permanent coarse filter pad allows good aquarium bacteria to thrive and provides biological filtration
  • Adjustable flow rate is not very precise and doesn’t change the rate very much
  • Lacks a separate media compartment, which limits the amount of media you can add to this model
  • Special outflow increases evaporation and mineral or salt build-up on your tank and equipment

2. Aqueon QuietFlow LED PRO

Aqueon QuietFlow LED PRO 75 Aquarium Power Filter
  • Capacity: Up to 90-Gallons
  • Dimensions: 14.2 x 9.2 x 7 inches
  • Flow Output: 400 GPH
Check The Price

 

I was torn on whether to label the Aqueon QuietFlow LED Pro as the quietest or the best for novice fish keepers. While this is a very quiet HOB, the AquaClear below is quieter. Novices can also benefit from Aqueon’s LED indicator light that flashes when it’s time to change the pads or when flow rates drop from a clogged filter!

This 3-stage filter comes with two removable bio-holsters and a third screen in the oxygen-rich outflow that provides space for bacteria to grow. Aqueon-branded filter cartridges fit inside these holsters, or you can customize the pads and media used. The clear housing makes it easy to see what’s going on inside the box, too!

Benefits Disadvantages
  • Quiet, self-priming 3-stage filter with two types of biological filtration
  • Clear plastic housing allows you to see inside your filter without opening the lid
  • LED light indicator tells you when the pads need replacement and when your flow rate drops
  • Flow rate is not adjustable
  • The impeller seems to require frequent replacement
  • Limited room for extra filter media

3. Marineland Penguin BIO-Wheel Power Filter

Marineland Penguin 100 gph BIO-Wheel Power Filter
  • Capacity: Up to 20-Gallons
  • Dimensions: 8 x 5.5 x 8 inches
  • Flow Output: 100 GPH
Check The Price

 

If you want the best hang on back filter for freshwater tanks I highly recommend the 3-stage Marineland Bio-Wheel. The specific features vary depending on the model, but the one here is the basic version, which is the smallest and suitable for tanks from 10 to 20-gallons. Of course, it has the patented Bio-wheel for biological filtration!

Inside, the powerful motor and impeller move your water through the replaceable filter pad with high-quality carbon chips before sending it through the Bio-wheel and back into your tank. You can easily customize the pad and media, however. The main downside is that Bio-wheels can be fussy to maintain and increase evaporation!

Benefits Disadvantages
  • 3-stage filter with patented Bio-wheel for biological filtration
  • Two-part lid makes it easy to access the inside of your filter box
  • You can use branded replacement pads/media or customize them for better performance
  • These filters are usually noisier than other designs and two-part lid can increase the noise
  • Bio-wheel dramatically increases evaporation, so not ideal for marine tanks or hard water habitats
  • Premium filter is usually priced higher than other models

4. Tetra Whisper Power Filter

Tetra Whisper Power Filter 10 Gallons Quiet 3-Stage Aquarium Filter byby Tetra
  • Capacity: 5 to 10-Gallons
  • Dimensions: 4.2 x 6 x 7.1 inches
  • Flow Output: 90 GPH
Check The Price

 

The best hob filter for 10-gallon tanks or smaller is the older and inexpensive Tetra Whisper. Don’t get it confused with the newer Whisper IQ, however, which has a different design. This simple system is fairly quiet, and features a 3-stage replaceable cartridge with Bio-foam for bacterial growth.

While the Tetra has a flow rate of 90 GPH the current produced is usually mild and doesn’t need to be baffled for Bettas. There’s nothing fancy about this filter and that includes the price, which is typically quite low. One downside to the Tetra is that it isn’t really a 3-stage filter since the bacteria gets discarded with the filter pads.

Benefits Disadvantages
  • Basic and inexpensive filter perfect for small tanks with a low bioload
  • Easy to find replacement pads and parts for Tetra filters
  • Naturally low flow and suitable for Bettas
  • Biologic media does not stay in the filter and is discarded with the pads, so not truly 3-stage
  • Cheap construction leads to vibration and noise especially as the filter ages
  • Flow rate is not adjustable

5. AquaClear 50 Aquarium Power Filter

AquaClear 50 Aquarium Power Filter
  • Capacity: Up to 50-Gallons
  • Dimensions: 4 x 9 x 8 inches
  • Flow Output: 200 GPH
Check The Price

 

If you’d like a Fluval HOB filter but don’t want to pay a premium price, then consider a model from their mid-range brand, AquaClear. These basic systems are no-frill, but are the quietest and some of the best filters on the market even so. They offer true 3-stage filtration with a filter box design that allows for endless customization.

Instead of using a wheel, the AquaClear has a lower layer of filter foam and upper layer with ceramic rings that harbors the good bacteria. Additional replaceable filter pads can polish the water and remove fine debris. You can add your media of choice in between the layers to provide the exact type of filtration your tank needs!

Benefits Disadvantages
  • Very quiet and user-friendly to operate, and has an adjustable flow rate
  • Water moves up from the bottom of the filter to the top so it does not by-pass the media stages
  • Allows for flexible set-up by customizing filter pads and media used to purify the water
  • Doesn’t include internal media baskets, so you may need to place the media in a mash bag
  • Flow rate is quite strong and many aquariums will need a sponge filter tip to prevent injury to fish
  • Not ideal for use with sand substrates, which can damage the impeller

6. Seachem Laboratories Tidal Power Filter

Seachem Laboratories Tidal Power Filter
  • Capacity: Up to 55-Gallons
  • Dimensions: 8.0625 x 5.5 x 7.75
  • Flow Output: 250 GPH
Check The Price

 

The best HOB filters for reef tanks are these old-school models from Seachem Laboratories. They resemble a 1990’s design on the outside, but the inside is completely modern. This is a great option for marine tanks because it has a built-in protein skimmer. It’s so packed with features I can’t even list them all here!

The Seachem has a large capacity filter basket and prevents water from by-passing the media and pads. If the flow drops or the filters get clogged, an indicator lights up, and the filter redirects the water back into the tank to prevent spills. Highly durable and customizable, the Seachem is a great option for salt and freshwater tanks.

Benefits Disadvantages
  • Large capacity media basket offers 3-stage filtration and allows flexibility in your set-up
  • Dual-intake with built-in surface skimmer
  • Indicator light alerts you to flow problems with your filter
  • Doesn’t have a clip to hold media baskets/bags in place, which is annoying if they shift
  • It’s not easy to access the impeller and may cause frustration for novice aquarists
  • Old-school exterior means it isn’t the best looking HOB

Conclusion

A green beautiful planted tropical freshwater aquarium with fishes

As you can see, HOBs are a great option for freshwater and marine tanks of all sizes and are ideal for both experienced and novice fish keepers. They are easy to set-up and maintain, and the hardest part is usually picking the best model for your tank!

With so many options in sizes, features and flexibility, nearly any tank can benefit from a HOB. If you’re still not sure which filter on my list is best for you:

  • The Marineland is my overall favorite and the best premium filter on the list, but if you need a filter for a reef tank, the Seachem would be the option I’d go with.
  • If you’d prefer a basic and inexpensive filter either the Tetra or the Penn Plax could be the choice for you, or the Aqueon if prefer a filter with a few more features.
  • The AquaClear may not be fancy but it is the quietest filter and has a solid design that functions like a premium filter. If you have hard tap water, I’d even pick the AquaClear over the Marineland to reduce the amount of time you spend cleaning mineral deposits off your tank

Jen has more than 30 years experience as a biologist, aquarist, and fishkeeper. She is an expert in setting up new tanks and maintaining naturally-planted freshwater habitats, and has experience raising a wide variety of aquatic species.

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