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With so many models on the market right now it can be hard deciding on the right hang on the back (HOB) filter for you. Most stores carry as many as a dozen brands and new models are leased each year.
That said, there are some brands that create stellar HOB filters. Whisper, Fluval Hagen, Seachem, and the others in this list have spent decades perfecting their design. So let’s take a closer look at the best HOB filters on the market right now!
In this post, I review the following 5 best HOB filters.
- Seachem Tidal Power Aquarium Filter **Best Overall**
- Aqua Clear Power Filter
- QuietFlow Aqueon LED Pro
- Tetra Whisper IQ Power Filter **Quietest Filter**
- Fluval C Power Filter
What is a Hang on the Back Filter?
Hang on the back filters are the most common style used by fish keepers. These filters are designed to attach to the lip of your aquarium and are usually hidden on the back or sides.
Aquarium water first gets sucked into the unit via an electric pump. Once inside the water is forced through several layers of mechanical, chemical, and biological filtration media. Each layer removes impurities that can impact fish health.
The purified water then flows right back into the aquarium only a few seconds after uptake! Efficient, easy to hide, and reasonably priced, HOB filters are preferred by the majority of aquarists!
They don’t have the flow or media capacity of canister filters but they are ideal for tanks with small to medium-sized fish.
Hang on the back filters also create enough surface agitation to facilitate gas exchange. Oxygen, nitrogen, and carbon dioxide are all easier to exchange when the surface is disturbed by an HOB filter!
5 Best Hang on the Back Filters
The hang on the back filter market has been crowded for some time so it’s great to see Seachem introducing a new line of filters. The Tidal series includes some brilliant, modern tweaks to a design that’s been around for decades.
By including a second intake valve at the waterline, the Tidal series can skim the surface of organic debris. These proteins can slow the exchange of oxygen, carbon dioxide, and other gases.
Flow is also adjustable, not only in terms of overall output but between both the surface and telescoping pipe. A heater clip also sits along the side, condensing much of your aquarium technology into a single, easily accessed area.
Most of the media that’s included with HOB filters is average quality. However, the Tidal includes Seachem Matrix, which is one of the finest biomedia options around.
Seachem Matrix has micropores small enough for the bacteria that eat nitrate and convert it to nitrogen to live in. Most other biomedia can only convert ammonia to nitrate, which then builds up until you perform a water change.
As your filtration media clogs with debris and bacteria overgrowth, water flow starts to get hindered. Often, you will see water bypassing the media rather than going through it for processing.
The Tidal HOB filters have an indicator that lets you know when water is bypassing, signaling that it’s time for a cleaning.
- Surface and deep water intake options
- Full flow customization
- Self-priming pump
- Average sized biomedia compartment
- Many features not available on smallest model (Tidal 35)
- Pricier models
One of the best features of the Aquaclear line is its simplicity. The design has been perfected over decades to work instantly and with minimal fuss. The magnetic impeller is near fail-safe and easy to re-align if knocked off-axis by a stray bit of gravel.
Flow can be adjusted via a switch on top of the unit. This is extra convenient for reducing flow during feeding or for small, sensitive fish.
These models have a huge amount of internal space for filter media; as much as six times that of equivalent brands. This allows you to use custom media alongside your usual choices for specific problems such as high ammonia or carbonates.
Rather than locking you into buying disposable cartridges, you have a three-stage mechanical, biological, and chemical filtration setup. A large foam block activated carbon package, and ceramic bio-rings are included to have you up and running in minutes.
The largest models (the 50, 70, and 110) also have an especially long outflow, perfect for disturbing the surface enough for good gas exchange.
However, the large splash zone, combined with the older pumps, can create a fair amount of noise. While not disruptive during the day, the Aqua Clear line might be a bit disturbing for a bedroom aquarium near a light sleeper.
- Large splash zone for good gas exchange
- Simple to operate and maintain
- Large media compartments
- Relatively noisy
- Not especially feature-rich
Aqueon uses a complex 5-stage filtration system that’s possible only when using the cartridges designed for their QuietFlow line. Each cartridge includes a layer of cotton floss to screen out heavy particles.
Within, the activated carbon layer absorbs dissolved organic matter. After water leaves the cartridge it flows through the Bio Holster which provides space for beneficial bacteria to latch onto ammonia and nitrites.
Most filters stop here and send water right back into your aquarium. However, the QuietFlow design adds space for a second layer of biomedia as well as a final block of foam coated in resins that lock up leftover ammonia and nitrites.
This is the best filter for overstocked tanks or fish with high bio loads like goldfish or cichlids. There is so much room for bio media that ammonia and other nitrogenous waste products should be a non-issue.
Each unit also includes an LED indicator that flashes when the interior water level gets high enough. This indicates that water is bypassing due to clogged media.
Like many modern pumps, the QuietFlow also uses a self-priming design that doesn’t risk failure or burnout if started dry. Older HOB filters had to be partially filled before turning on.
You can place the QuietFlow Aqueon right on the side of your tank and plug it in out of the box. The pump will immediately pull water into the unit and safely start running.
- Reliable, self-priming magnetic pump
- Tons of space for bio media
- LED indicator for regular maintenance
- Cartridges can add up over time
- Needs several different types of media for full performance
Tetra Whisper filters have been around forever and have only gotten better over time. The Whisper IQ line is especially impressive in how well they handle noise.
Each unit includes a soft SoundShield barrier that isolates the motor from the rest of the unit. Combined with the compact, dense polymer design, vibrations are thoroughly dampened. This is the best model for bedrooms and other noise-sensitive spaces.
Whisper also includes your choice of two filter cartridge styles: a standard design using cotton floss and activated carbon and one that includes Stay Clean tablets.
These tablets use slow-release agents that bind to floating particles over time. Doing so makes them large enough to be screened out by the filter or sink to the bottom. This improves water clarity, especially in tanks with a lot of organic debris, like planted aquariums!
The flow rate is entirely adjustable to allow for additional surface agitation when needed. Yet you can also reduce it for slow-moving fish like bettas or to avoid disturbing floating plants.
The Whisper IQ line are also some of the most affordable HOB filters on the market! If you’re looking for efficient, capable filtration on a budget these are by far the best filters to work with.
- Filter is perfectly designed to dampen sound
- Very affordably priced
- Stay Clear tablets for added water clarity
- Not especially feature-rich
- Much less space for bio media
The Fluval C is a five-stage filter that provides space for all three types of filtration needed for a good HOB design! The initial stage uses two grades of filter floss; a coarse layer for large particles and a second, finer layer for smaller pieces.
Should this layer begin to get clogged a flow indicator on the cartridge protrudes, letting you know the Fluval C needs maintenance.
A chemical filtration chamber provides space for any sort of media you prefer, from activated carbon to ammonia-absorbing resin. Many aquarists also opt to include additional bio media here.
Lastly, a trickle chamber provides space for bio media to evenly process the water before returning back to the aquarium. To get a better look at how the Fluval C is designed, check out Fluval’s maintenance breakdown of the unit!
The modular design makes both maintenance and customization significantly easier. While the Fluval C technically uses cartridges the foam is replaceable. This allows you to buy in bulk or adjust the mechanical media to meet your needs!
Fluval also designed this unit with potential bypassing in mind. Water actually circulates through the stages several times before being released back into the aquarium.
This recirculation process does slow the outflow and reduce surface agitation for gas exchange. However, this also makes the unit not only better at processing waste but quieter as well!
- Recirculates water for additional polishing
- Modular, customizable design
- Very affordably priced
- Provides less surface gas exchange
- Needs more space behind the tank than other brands
So Which is the Best HOB Filter?
However, the overall best HOB filter is the Seachem Tidal Power Aquarium Filter. It not only provides space for each stage of filtration but provides something no other HOB filter does: surface skimming.
The Seachem Tidal comes with Seachem Matrix, the best bio media on the market for its denitrifying ability. And the Tidal units include advanced flow controls, a clip for your heater, and a flow indicator for when the unit needs changing.
For all this capacity the Seachem Tidal is very reasonably priced. But if you find the price high compared to the other models, any one of these is an excellent HOB filter that will meet your mechanical, chemical, and biological filtration needs! So choose well and good luck caring for your fish!
Understanding Hang on the Back Filters
What are the Different Stages of Filtration?
Nearly all filters provide three types of filtration: mechanical, chemical, and biological filtration. While some focus more on one versus others, you should be looking for a unit that handles all three of these stages!
The first stage is the simplest and most obvious! Mechanical filtration uses a mesh screen typically made of plastic or cotton to trap floating particles.
Many HOB filters use two mesh sizes. First, grab larger particles like dead plant leaves and fish poop, and then a second stage of finer mesh to polish the water of bits of uneaten food or algae.
Since it screens out the largest particles the mechanical filtration stage is usually the first and fastest to need maintenance. You may need to change your foam or cotton pads weekly to biweekly in a heavily stocked aquarium.
Chemical filtration is the most diverse stage because you can customize it to address nearly any issue! Most HOB filters include activated carbon packets or cartridges within a pouch of cotton media.
Activated carbon is really good at latching onto dissolved organic molecules. Free-floating proteins, dissolved amino acids, and other molecules that would otherwise feed bacteria rare instead trapped by the carbon.
You can then dispose of the carbon biweekly or monthly and replace it with fresh charcoal. Other chemical filtration options include resins like Zeolite that suck up ammonia and nitrite.
Others still are designed to filter out phosphorus, heavy metals, or carbonates. Chemical filtration is the Swiss Army knife of your aquarium and you should always be ready to change it as needed to address an issue!
Biological filtration is typically the last stage before water is sent back into the aquarium. This stage relies on a live culture of nitrifying bacteria which takes weeks to grow. This process is called the nitrogen cycle.
Once in place, these bacteria latch onto nitrogenous wastes. These chemicals include ammonia, nitrite, and nitrate.
Ammonia is released directly from fish and from microorganisms feeding on rotting organic matter. It is quite toxic if allowed to build up and can cause scale burns, gill irritation, and death if it’s not removed.
Ammonia is broken down by these bacteria into nitrite, which is less toxic but still not great. Nitrite can also be broken down by a second group of bacteria into nitrate, which is even less toxic.
Nitrate typically then sits in the aquarium until removed by water changes or taken up by plants and algae. However, if your substrate or bio-media has pores small enough, you can generate a colony of denitrifying bacteria.
These specialized microbes eat nitrate and convert it into nitrogen gas, which outgases into the air. However, denitrifying bacteria are anaerobic, meaning they are killed by oxygen.
They need tiny, isolated pores where oxygen can’t get at them to thrive, so specialized media like Seachem Matrix are the only way to get a good colony established.
If you’d like to learn more about how biological filtration and beneficial bacteria help keep your fish healthy, check out this video below!
HOB vs Other Filter Designs
The four most common filtration designs are: hang on the back, sponge, canister, and under gravel filtration. And of these, sponge and HOB are probably tied for the number 1 spot in popularity.
Whenever you have the choice, I’d always opt for a HOB filter over a sponge filter. Sponge filters provide great mechanical filtration capacity and decent biological filtration.
However, they provide no chemical filtration capacity at all. There are a few sponges infused with carbon. However, they still need replacing, meaning you’re better off with a HOB filter anyway.
The only time sponge filters are best is if you’re dealing with livestock that require pristine water but are sensitive to flow. Fish fry, small shrimp, and other animals can’t resist the flow of an HOB filter but will thrive if provided a small sponge filter.
Canister filters are top-shelf technology in the aquarium filtration world. They provide the highest flow rates and the largest, most customizable media compartments available. However, they can be overkill for the majority of hobbyists and much more expensive than most HOB filters.
Undergravel filters were once very common decades ago but have become less so with the high tech options available today. They use water flow to pull debris into the substrate where it’s trapped until you vacuum the bottom.
Paired with a high surface area media like crushed lava rock, they can provide plenty of mechanical and biological filtration. However, they are easily disturbed and provide no chemical capacity at all.
Hang On Back style aquarium filters have been the go-to filter for small aquariums for quite some time. They are affordable, easy to install and do a great job filtering fish tanks. I hope this has given you enough information to make an educated decision on which HOB filter is best for you!