Undergravel Filter Vs Power Filter And Using Them Together

What’s the difference between an undergravel filter vs power filter? Can you use undergravel filters and power filters together? Those are the questions I’ll be answering in this post!

Undergravel and power filters have different functionalities, but some people still like to try them out together. 

We’ll take a look at what these are, how they work, and when it might make sense to combine them into your aquarium setup. Let’s dive right in!

Undergravel Filters VS Power Filters (A Head To Head Comparison)

Undergravel filters and power filters are different pieces of equipment altogether. They are different in terms of mode of operation, filtering capabilities, shapes, and sizes. 

Undergravel filters operate by an air pump or a powerhead and are well known for primarily biological filtration. While power filters are run by an electric pump and can provide all three types of filtration. However, filtration efficiencies are not as high as canister filters. 

There are advantages and disadvantages of both undergravel and power filters. In the later sections, you’ll get an in-depth overview so that you can make an informed decision on which filtration system you should choose. 

What Is An Undergravel Filter?

The undergravel filter is an innovative way to keep your tank clean. It’s a rectangular grating or plate that sits at the bottom of the aquarium containing many holes or slots for water to pass through. 

Water from above flows down over this plate and then passes out through piping called lift tubes which function as outlets on either end. Gravel or substrates that remain over the plate work as filter media. You need an air pump or powerhead to begin the filtration. 

Undergravel Filter Nutshell Summary

How To Set Up An Undergravel Filter?

Some people like to use an undergravel filter for their fish tanks. It is easy and doesn’t take up too much space in the aquarium. To start off, you’ll need a few things, and most importantly, you’ll need an empty aquarium. 

  1. Place the plate at the bottom of the tank and connect lift tubes. 
  2. Use a couple of inches thick gravel or substrate that’s coarse enough to cover the screen. 
  3. Use tubings to connect the air pump with the lift tubes. 
  4. Fill the aquarium with dechlorinated water and turn on the air pump, and you’ll notice that bubbling started. 

How Do Undergravel Filtration Systems Work?

The process of undergravel filtration uses the substrate in your aquarium as a filtering element to trap debris. Substrates also work as an excellent medium for beneficial bacteria. The suction is created by either air pumps or powerheads to circulate water through the substrates. 

There, ammonium and nitrites are converted into nitrates by colonies of bacteria on these substrates. The water filtered in the substrate layers eventually gets back to the aquarium from a tube at the top. 

The lift tube usually contains an elbow; this carries activated carbon for chemical filtration purposes, which strips out toxins, odors, etc.

Should I Use An Undergravel Filtration System: Pros And Cons

Should you use an undergravel filter in your aquarium? It’s a tricky question to answer because it depends on your requirements. But before making decisions, it’s better to understand the pros and cons of an undergravel filter. 

Advantages Of Undergravel Filters?

  • Undergravel filters are a favorite among aquarists. They’re so cheap that it doesn’t matter if the tank is as small or big; your new filter will fit right into your budget!
  • Undergravel filters use all the substrate surface area to grow nitrifying bacteria, improving biological filtration better than any other filter. Water has to go through the entire substrate before going up towards its tube. Along this way, every layer gets oxygenated, which helps promote good bacteria. 
  • Thanks to the large bacteria colonies, an undergravel filter can support the tank ecosystem for an extended period during a power outage. The maintenance requirement is also very low; weekly or bi-weekly vacuuming the gravel is sufficient. 
  • Undergravel filters are highly beneficial for small planted tanks because aquatic plants can use nutrients in the substrate, resulting from decaying debris, fish waste, etc. You can create a self-sustaining ecosystem for your aquarium using the undergravel filter because it helps to develop synergistic relationships between your fish, plants, and water chemistry all at once!
  • It’s reliable and durable and compatible with other filters. If you think your tank needs extra filtration, such as for heavily stocked tanks or greater bioloads when an undergravel filter alone isn’t enough of a solution, using another type along with the UGF can easily be done.

Disadvantages Of Undergravel Filters?

  • Undergravel filters provide mechanical filtration up to some extent, and you can customize it to boost chemical filtration as well. However, it’s still minimal and may not be sufficient for larger setups. 
  • Plastic screens limit the types of substrates you can use in your aquarium. Only coarse substrates are ideal to use; fine sands or soils will fall through the screen holes. 
  • You need an empty aquarium to set an undergravel filter, and once you do that, it’s not possible to adjust. Moreover, you’ll have to break your tank down to clean the biofilm sludge that accumulates under the screen every year. 
  • Suppose you are switching your filtration system to an undergravel filter. In that case, it may not be very effective for a few months initially because it takes time for bacteria to colonize. 

What Are Power Filters?

A power filter is an enclosed casing that has everything you need to clean the water in your aquarium. The container features a pump, filter media, a water inlet, and an opening to release the filtered water. Power filters sit on the back of the tank or inside the tank. 

The electric pump pushes the water through the filter media. It provides three-stage filtrations, removes debris, and toxins, and also offers biological filtration. Power filters can be used as a standalone filters for aquariums up to 50 gallons. 

What is a power filter

How To Set Up A Power Filter?

Power filters are ready to go and straightforward to install. You can do it in a few simple steps. 

  • Unbox the filter and check if the motor and impeller are in good condition. 
  • Rinse the filter media in freshwater. 
  • Install the cartridges, sponges, and media baskets in their designated place. 
  • Hang the filter on the back of your tank or securely place it inside. 
  • Prime the pump with water if needed, and turn on the filter. 

Types Of Power Filtration

Two main types of power filtration systems exist: internal and HOB (hang on back). For nano tanks or small fish bowls, an internal filter can be used. This sits inside the aquarium with no external parts needed on top.

Related Article: 5-Gallon Fish Tank: What’s The Best Aquarium Filter?

However, for larger setups, the best power filter option is a HOB (Hang on Back) system that is more robust in design compared to internal filters. 

How Do Power Filtration Systems Work?

HOB power filters are more powerful than internal power filters, but both function similarly. 

The filtration process starts with the impeller turning and pulling water up into the filtration chamber. It is then filtered with the help of filter media and sent back into the tank through an opening as clean water. 

The first step filters large debris caught by filter sponges or pads, while pieces of carbon or bio-media absorb toxins during later stages until it becomes purified for use in your aquarium fish’s habitat. 

Pros And Cons Of Power Filtration System

Power filters are excellent choices for your aquarium. What are the advantages and disadvantages? Let’s know in detail. 

Advantages Of Power Filter?

  • Power filters are efficient in removing debris and toxins from the aquarium water. However, a single unit is not suitable for larger tanks (above 75 gallons); multiple units may help to keep the tank ecosystem healthy. 
  • In addition to making your tank clean and healthy, power systems also make things easier for you. You will have fewer water changes than undergravel filters, which means more time enjoying the fish than maintaining them!
  • Power filters are adjustable and easily removable for cleaning or relocation. Moreover, they are usable in planted tanks as well as highly-stocked fish tanks. 
  • The media in HOB-style filters remain accessible while the filter is operating, so you won’t even have to reach into the water to change it! However, you have to get the media by dipping your hand in the water for most internal power filters. 
  • Aquarium filter media used in power filter systems are usually customizable according to your tank needs, and various options are available. 

Disadvantages Of Power Filters?

  • Power filters aren’t capable of delivering as much biological filtration as undergravel filters can. 
  • Another disadvantage of power filter systems is that they don’t circulate water adequately. This means the current may not be strong enough for large aquariums, requiring more than one filtration system.

Which Is Better: Undergravel Or Power Filtration System?

Filtering Capabilities

Undergravel systems are great for plants, but they don’t clean debris or purify water as efficiently as power filters. However, they provide much better biological filtration.

Undergravel Filter Vs Power Filter - Filtering Capabilities

Power filters are better at removing waste because of their essential three-stage filtration. Some advanced power filters also feature added bio-stages, like bio-wheels or bio-sponges to boost filtration biologically. Moreover, media mixes are customizable, which you can take advantage of depending on your needs. 

Set-Up and Ease-of-Use

Undergravel filters are easy to use, and installation is also not very difficult. But the criteria is you need an empty tank. And once installed, you can’t easily make adjustments unless you break down an established tank to the bare bottom. 

Undergravel Filter Vs Power Filter - Set-Up and Ease-of-Use

On the other hand, power filters are easier to set up, relocate and adjust whenever you need them. You’ll have much more flexibility in terms of location and choices of media. 

However, as it is run by an electric pump, it needs a bit more attention. HOB power filters hang outside the tank; you can’t nullify the possibility of springing a water leak. 

Moreover, if the pump is not self-priming, you need to prime the pump manually; otherwise, dry running may burn out the motor wiring. Fortunately, Hang on Back (HOB) filters with self-priming pumps are readily available; you can get one to cancel out this issue. 

Above mentioned issues don’t apply to internal power filters because they remain submerged under aquarium water. However, the capacity is less compared to HOB filters. 


Large debris like fish poop or dead leaves have no choice but to accumulate on top of your substrate; you must vacuum them up on a weekly or bi-weekly basis! In addition,  weekly water changes are necessary to keep the water parameters healthy for fish. 

Undergravel Filter Vs Power Filter - Maintenance

When it comes to weekly or bi-weekly maintenance, undergravel filters are an easy way to maintain. But, it’s daunting when they require yearly cleaning. They can stop working if the build-up of biofilm under the screen is not cleaned out. 

It’s recommended to clean that out once a year, and you need to empty out the whole tank to reach the filter plate, a lot of work, indeed!

Power filters are effortless to maintain in Comparison to undergravel filters. You can easily remove them and change the filter cartridges when required. However, maintenance requirements vary depending on the bioloads, and media types. Therefore, you’ll have to figure out the frequency of routine maintenance to keep everything inside the aquarium normal. 

Sometimes, the motor housing or impeller may get clogged. You need to disassemble the unit to clean; however, it’s not as tricky as yearly maintenance of undergravel filters. 


When it comes to aquarium filtration, the undergravel system is definitely a cheaper option. But if you add the amount of buying an air pump separately, it may cost the same as a power filter. 

Undergravel Filter Vs Power Filter - price

Therefore, in terms of price, effectiveness, and long-term benefits for your fish tank’s health, you may be better off with modern power filters.  

What If Using Undergravel And Power Filters Together?

Yes, it’s an excellent option that you can consider. An undergravel filter is a great way to get superb biological filtration in your community tank. If you combine it with a power filter system, like a HOB or the internal submersible filters, then you would have top-notch mechanical, chemical, and biological filtration in your tank. Combining them will benefit you in many ways, although it costs you a few extra bucks. 

  • Power filters and undergravel filters will complement each other.
  • Cleaning and maintenance frequency will be lower when both are running in tandem. 
  • You can delay the yearly cleaning of undergravel filters because power filters will take care of most mechanical and chemical filtration. Therefore, the accumulation of biofilm under the plate will be less. 
  • Fewer water changes will be required. Instead of weekly water change, you can do that bi-weekly. 


Choosing a power filter over an undergravel has become more popular these days. Both filters are priced similarly, but HOBs or internal ones provide much better filtration for less work required to maintain them.

Since most people who buy undergravel get tired of cleaning the gravel weekly, it makes sense to skip that step and purchase a quality power filter instead. However, you can use them together in your tank, especially in a planted or aquascaped tank. 

Sujit Modak

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