external power (Hang On Back) filter

Power filter (Hang-On-Back or HOB filter) is one of the best aquarium filters for small to medium tank size. It is also the most popular filter on aquatic hobby today because of its being very affordable price and powerful features far superior than other filter types. The most well-known brands can be mentioned are AquaClear, Aqueon QuietFlow, Fluval C series, Marina Slim S series, Marineland Penguin… that are covered in this review.

How does an aquarium power filter works?

Power filter is also called as HOB (Hang On Back) filter because it is placed and works out side of the tank, usually hang on the rear side of aquarium. It is the most common type of filters purchased by aquarists, particularly for their 10 to 55 gallon tanks. This filter type is very powerful to keep your fish tank clean, easy to set up, maintain and most importantly less expensive than a canister filter.

external power (Hang On Back) filter

When working, the power filter sucks water into its filter capacity via the intake tubes and later through the filter materials that perform 3 types of filtration before the clean water is returned to the aquarium from the top.

  • Mechanical filtration is usually performed by filter cartridges (filter pads), foams, flosses that trap solid matters in aquarium water allowing manual removal.
  • Biological filtration is usually performed by Ceramic Rings or biological filtration pads to degrade Ammonia (NH3) and nitrite (NO2) that can cause harmful for your fish and invertebrates.
  • Chemical filtration is usually performed by Activated Carbon or cartridges coated with Activated Carbon to trap some organic chemical compounds in the water to keep the clarity and prevent the odors.

These filters are typically rated for 75 gallon aquariums on the high end and in most cases I would recommend trying to avoid “maxing out” your filters recommended tank volume. (i.e. 75 gallon rated HOB = use for max 55 – 60 gallon aquarium). Following are the best power filters on the market today.

Aqueon QuietFlow 10 LED PRO for tanks up to 10 gallons

Aqueon QuietFlow 10 is designed to operate so quietly and reduce the likelihood of leaks that are common problems of many power filters after a time of use. It features a flow rate of 100 gph and is suitable for aquariums up to 10 gallons. It features a unique internal pump, which does not need to be primed manually after cleaning or power failure.

Aqueon QuietFlow four-stage filtrationAqueon QuietFlow four-stage filtration

This filter features 4-stage advanced filtration. Stage one uses dense floss to remove debris and particles. Stage 2 uses activated carbon to remove odors, discoloration, chemical toxins, and heavy metal. Stage 3 uses patented Bio-Holster to remove toxic nitrites and ammonia. And stage 4 uses a diffuser grid to neutralize more toxins while increasing oxygen exchange for healthier fish.

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AquaClear 110 power filter for 60-110 gallon aquariums

  • AquaClear 110 power filterEditor's rating: Check on Amazon.com
  • Max flow rate: 500 gallons per hour (gph), adjustable
  • Ideal for: 60-110 gallon fish tanks
  • Media: foam, activated carbon, Bio-max
  • Warranty: 2 years from date of purchase
  • In this series:
  • AquaClear 20 (100 gph, for 5-20 US gallon tanks).
  • AquaClear 30 (150 gph, for 10-30 US gallon tanks).
  • AquaClear 50 (200 gph, for 20-50 US gallon tanks).
  • AquaClear 70 (300 gph, for 40-70 US gallon tanks).

AquaClear 110 power filter is one of the most flexible HOB filters currently in the market. Its unique design enables you to put a large amount of media in the large filter chamber and allows for very long media-water contact time for the most efficient filtration. The large filter chamber makes it flexible of using filter media and allows you to choose your favorite ones. It comes with an efficient pump that lowers operation costs.

The filter achieves the maximum flow rate of up to 500 gallons per hour and is ideal for 60-110 gallon aquariums. Its patented re-filtration system lets you reduce the flow up to 50% without interfering with the efficiency of filtration. When you lower the flow rate, the water within the filter chamber is processed multiple times to make it ultra-clean and maintain the filtration efficiency.

Cycle Guard with BioMax. Source: Fluvalaquatics.com

The power filter features CycleGuard multi-stage filtration mechanism, which provides optimal chemical, biological and mechanical filtration. It is very easy for you to install the filter with foam at the bottom, activated carbon in the middle and Bio-Max ceramic rings at the top. The foam filter should be replaced after 2 months, activated charcoal after a month, and BioMax after 3 months.

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Fluval C4 power filter for tanks between 40 to 70 gallons

  • Fluval C4 power filterEditor's rating: Check on Amazon.com
  • Flow rate: 264 gph, adjustable
  • For tanks: between 40 to 70 gallons
  • Media: poly/foam pad, activated carbon, bio-screen and C-nods
  • In this series:
  • Fluval C2 (119 gph for 10-30 gallon tanks)
  • Fluval C3 ( 153 gph for 20-50 gallon tanks).

The Fluval C4 power filter is specifically designed to provide maximum contact surface between water and filter materials in all stages of filtration to increase the efficiency. The result is clean, fresh, clear and healthy aquarium water for active and happy fish.

Fluval C series filtration

Image from Fluvalaquatic.com.

The maximum flow rate of the Fluval C4 is 240 gallons per hour. It comes with a patented re-filtration system, which lets you adjust the flow rate up to 50% without interfering with filtration efficiency. This filter is designed to provide 5-stage filtration including poly/foam pad for mechanical filtration, activated carbon for chemical filtration, and bio-screen and C-nods for biological filtration. It also features a light indicator to remind you when the poly foam pad need to be cleaned.

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Seachem Tidal 55 power filter for tanks up to 55 gallon

The Seachem Tidal 55 is designed from the ground up in order to provide your aquarium with comprehensive, high-quality filtration. The compact, hang-on style makes them easy to use and adaptable to various aquarium conditions both freshwater or saltwater. It features dual water intake with surface skimmer (8), self-priming pump (6), large filter chamber (3), and maintenance monitor (2).


Image from Seachem.

The filter filters 250 gallons of water per hour and is suitable for tanks up 55 gallons aquarium. Its fully adjustable flow regulator (9) allows to adjust performance to meet the need of your specific aquarium volume as well as the type of fish kept in the tank. Its large capacity filter basket (3) can accommodate any type of Seachem filter media. The package comes with a foam filter and Seachem’s Matrix bio-media to get you started. You can interchange the media to place them in custom configurations.

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Marina Slim S10 power filter for aquariums up to 10 gallons

The Marina Slim S10 power filter features a unique and compact design, which takes up less space than comparable filters currently in the market. It comes fitted with an adjustable flow control that makes it an ideal choice for small tanks under 10 gallons with small fish. The best features of Marina Slim S10 power filter is the very quiet operation pump. It can start itself after installation, cleaning or power interruption without the need of manual priming.

This filter is fitted with two filter cartridges. The first is Bio-Carb and the second is Bio-Clear. Both of the cartridges are fitted with Ceramitek, which is technologically engineered to maximize biological filtration for the health and vitality of your aquarium inhabitants. If you are finding a new filter with advanced biological filtration system to keep your fish healthy, the Marina Slim S10 is a great choice.

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Tetra Whisper 40 power filter for tanks up to 40 gallons

The Tetra Whisper 40 power filter has an adjustable flow rate of 200 gallons per hour that is strong enough to keep tanks up to 40 gallons clean and clear. The flow control dial mounted on its top allows you to easily adjust the flow rate to meet your aquarium need. It is very helpful for you to lower the flow rate during the feeding time of your fish to keep food particles out of the filter.

Tetra Whisper filtration systemTetra Whisper filtration system

The Whisper Bio-Bag cartridges are designed with activated carbon included in a two-side floss for mechanical and chemical filtration. Mechanical filtration removes bits of fish and plant waste and uneaten food while chemical filtration used activated carbon to remove compounds that discolor water and cause odor. The biological filtration, which is performed by bio-foam, stimulates the growth of beneficial bacteria to remove harmful ammonia and nitrite toxins in the water. It also allows you to choose additional media for filtration.

The unit also features a specifically designed reservoir that prevents back siphoning of aquarium water in the event of power interruption. The design is simple making this filter extremely easy to use, clean and maintain. There are four available models for small to large tanks up to 60 gallons.

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Marineland Penguin 200 power filter for 30-50 gallon tanks

Designed for 30-50 gallon aquariums, the Marineland Penguin 200 is an excellently built and durable HOB filter that can be used in a variety of aquarium setups. The certified flow rate of this filter is 200 gallons per hour but it allows you to easily adjust the water flow using the mid-level strainer attached to the intake tube.

The filter uses a patented Rite-size C cartridge floss pad with activated carbon included, which screens out debris and dirt. The activated carbon inside the cartridge ensures efficient chemical filtration that removes harmful heavy metals, impurities and discolorations. The cartridge uses a patented ribbed back to optimize the contact between water and the activated carbon for better chemical filtration.

Unlike other biological filtration stage in other power filter brands using ceramide rings or bio-foams, the Marineland Penguin filters use patented Bio-wheels to help the growth of helpful bacteria required for biological filtration. These Bio-wheels spin during operating that increases the gas exchange on their surface to provide an ideal environment for helpful nitrifying bacteria to thrive in. These beneficial organisms then deal with harmful nitrogenous toxins to protect your aquarium friends.

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Aquatop PF40-UV Hang-On filter with UV sterilization

Unlike the other aquarium filters reviewed so far, the Aquatop PF40-UV hang-on is both a filter and a UV sterilizer. The UV sterilization is very helpful in eliminating harmful parasites and unwanted algae blooms which freely float in aquarium water. Moreover, it come with a built-in self-adjusting surface skimmer to clean the aquarium surface and promote gas exchange. The added UV sterilizer and skimmer require no extra plumbing and is ready to install and use.

The Aquatop PF40-UV comes with an adjustable flow rate of maximum 128 gph and is ideal for aquariums up to 40 gallons. The filtration process is five stages including filter pad with Aquatop’s bamboo carbon for mechanical and chemical filtration, ceramic rings for biological filtration, UV sterilizer, and surface skimmer. The filtration media are easily replaceable to ensure that the maintenance is easy and quick to do.

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Penn Plax Cascade Hang-On aquarium filter

Penn Plax Cascade Hang-On aquarium filter is a great hang-on filter to buy. It features a nice, compact design that will complement your aquarium while at the same time ensure that your favorite pets are healthy and safe. It is designed to attach to your tank effortlessly by simply sliding over the edge of the glass. The intake tube is built with an extendable stem, which allows the intake strainer to reach closely to the bottom of your aquarium.

The filter has an adjustable flow rate of up to 300 gallons per hour and is suitable for 55-100 gallon aquariums. The mechanical filtration is provided by the polyfiber floss, which traps floating particles. The activate carbon cartridge removes toxic chemicals, discoloration and odor. And the internal sponge stimulates the growth of beneficial bacteria. The external Bio-Falls dry/wet biological booster enhances the work of anaerobic bacteria for additional ammonia and nitrite elimination while enhancing aquarium oxygenation.

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Tetra Whisper EX70 for 45-70 gallon aquariums

The Tetra Whisper EX70 features an elegant, lightweight and compact design making it ideal for aquariums of up to 70 gallons. It has an easy access door situated on its top that remains in place while you are changing the filter cartridges. It also has a unique filter cartridge carrier that helps you to keep your hand away from the harmful used cartridges and preventing unnecessary drippings. The filter features a submersed motor that requires minimal maintenance.

Tetra Whisper EX70Tetra Whisper EX70

The Whisper EX70 achieves a flow rate of 340 gallons per hour. From the information provided by the manufacturer, it is not clear whether the flow rate is adjustable. The filter directs water through several floss layers of the cartridge to remove the most particles. Its coarse floss helps to remove solid particles while the carbon inside removed odors, toxins, and discoloration. Unlike other filters, the biological stage of the Tetra Whisper EX series is performed by patented Bio-scrubbers, which provide the house for helpful bacteria to thrive in.

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