Best Undergravel Aquarium Filters: Which One To Get For Your Tank?

An undergravel aquarium filter is a filter used for mechanical and biological filtration of water in the aquarium. In its basic design, it is a rectangular plate structure that is kept under a gravel substrate.

The filter or set of filters sucks water through the substrate. Water thus passing through the substrate layer gets rid of its impurities in the substrate and comes out clean and clear. In the process, the filers also provide a large space for beneficial bacteria to live and survive to trigger biological filtration.

Many sellers offer different varieties of UGFs. So, among so many different filters, you may find it difficult to select the best one for your purpose.

In this article, we will review the top 5 best Undergravel Aquarium Filters. We will also share with you some important information related to their working and buying tips to help you select the most suitable one for your requirement. So, here is the list of the top 5 best undergravel aquarium filters.

Top 5 Best Undergravel Aquarium Filters

  1. Penn Pax Premium Under Gravel Filter System – Best Overall
  2. Aquarium Equip ISTA Under Gravel Filter – Best for Budget
  3. Lee’s 115/125/150 Original Undergravel Filter – Best Premium Pick
  4. Aquarium Equip Undergravel Filteration Bottom Circular Bar
  5. XMHF Aquarium Fish Tank Undergravel Plastic Filter Board Air Tube

Penn Pax Premium Under Gravel Filter System– Best Overall


  • Aquarium Size: 40 Gallon Tank, 50 Gallon Tank
  • Total Dimension: 46”L x 11.5”W
  • Individual Plate Size: 11.5” x 11.5”
  • Number of Plates Included: 4

Penn Plax has been one of the most trustworthy names in the field of aquarium accessories. The Premium Clear Free undergravel filter offered by them further enhances their reputation.

The filter system is equipped with everything that you will need for your 40 and 50-gallon tanks. Thanks to highly effective mechanical, biological, and chemical filtration, the high-quality filter system delivers crystal clear water to pamper your most lovable fish in the aquarium.

The filter works equally efficiently on saltwater and freshwater.

Each Penn Plax filter includes 4 filter plates which are firmly secured together to ensure that the gravel remains within the filter plates. In addition to the filter plates, the system also includes jumbo 1” lift tubes.

The lift tubes offer enough surface area for effective filtration. You can adjust these lift tubes up and down as per the size of your aquarium.

This feature offers tremendous flexibility to the entire filter system. The system uses high pore air stones which allow air to flow without any blockage, exerting strong and steady pressure to impart enough power to the filters. 

The unique Filt-A-Carb filter cartridges offer highly effective chemical filtration. Depending on the quality of water and other factors affecting its quality over time, each cartridge can provide clear water in your aquarium for 1½  to 2 months.

The best feature of the cartridge is that the cartridges are very easy to change and need a few seconds to fit the new ones.

Not only is the cartridge replacement but it is pretty easy and quick to assemble even the filter system in your aquarium. You can assemble the whole system in a few minutes and then connect it to the air pump or powerhead to start effective filtration.

The filter system fits in the aquarium discreetly thus keeping the view free of clutter caused otherwise by additional equipment inside the tank.

Surprisingly, Penn Plax offers all these high-quality features in a highly affordable price range. Showing confidence over its product, Penn Plax offers a 100% money-back guarantee on their Clear filter.

Overall, the Penn Plax Clear Filter is one of the most efficient undergravel filtration systems having all the required features to keep your aquarium water crystal clear at all times.


  • No efforts needed in setting up and maintaining the system
  • Tubes are not quite robust and sturdy
  • Perfect for large tanks of 40 and 50-gallon capacity
  • Mechanical, biological, and chemical filtration
  • Offers excellent value for money


  • Tubes are not quite robust and sturdy

Aquarium Equip ISTA Under Gravel Filter – Best Budget



  • Aquarium Size: 5 Gallon Tank, 5.5 Gallon Tank
  • Total Dimension: 11.8” by 5.9”
  • Individual Plate Size: 11.8” by 5.9”
  • Number of Plates Included: 1

One of the most affordable UGFs in the market, the Aquarium Equip Insta is one of its class. This filter system can be used with multiple circulating systems like filter pumps and powerheads.

Besides, it can also be used with an air pump and hang-on-back types of filters to improve water circulation in your aquarium.

The ability to connect with so many systems significantly improves its capability of mechanical and chemical filtration in a variety of environments. The gravel bed offers enough area for Nitro-bacteria to grow and provides highly effective cleaning of tank water.

The 11.8”x5.9” filter size is perfectly suitable for small tanks with 5-5.5 gallon capacity. Besides, the filter system also consists of a lift tube that can be connected to each plate.

The tube can be adjusted as per your tank height. Moreover, the tube is designed to operate silently. It provides an absolutely noiseless operation to the entire filter system.

The filter system has the provision to install air stones in the tube. The design is such that airstones neither will pile up nor collapse.

The UGF is suitable for both saltwater and freshwater. There aren’t any other filter media in the system and only the gravel bed is used for the filtration purpose. The filtration system does not include any activated carbon cartridges, therefore, it is not suitable for the applications requiring chemical filtration.


  • Possible to connect with many circulating systems like air pump, and powerhead, etc.
  • Effective for both saltwater and freshwater
  • Highly affordable price range
  • Perfect for small aquariums
  • Can work with airstones
  • Quiet operation
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  • Chemical filtration is not possible

Lee’s 115/125/150 Original Undergravel Filter – Best for Premium


  • Aquarium Size: 50 Gallon Tank, 60 Gallon Tank
  • Total Dimension: 15” by 72” or 12” by 84”
  • Individual Plate Size: 14.25” by 11.5”
  • Number of Plates Included: 6

Lee has been in the field of aquarium filtration systems and accessories for a long time. It has made a name for itself during these long years. Lee’s Original Undergravel Filter has a multi-level plate design.

Made of high-resistant plastic, the plates offer very high durability to the filtration system. Unlike other inferior quality filters, filter plates in Lee’s original do not crack or get damaged by the weight of the gravel substrate and the water column.

The filtration system is perfectly suitable for large tanks. You can use this outstanding filtration system in the tanks with a length of 48” having a capacity ranging from 55 to 60 gallons.

The system comes equipped with two bottom plates. Besides, it also comprises four lift tubes. The tubes can be fitted with many different circulating systems like air pumps, water pumps, powerheads, or canister filters simultaneously. It can work equally effectively with saltwater and freshwater.

Lee’s Original offers all three filtrations viz. mechanical, biological, and chemical filtration.


  • Comprise carbon cartridges for chemical filtration]
  • Perfect for both freshwater and saltwater
  • Making material is of top-class quality
  • Robust, sturdy, and crack-resistant
  • Many ports for tube connecting
  • Ideal for newbies


  • Filter tubes are not sufficiently long

Aquarium Equip Undergravel Filteration Bottom Circular Bar


  • Aquarium Size: 55 Gallon Tank
  • Dimension UP Bottom circular Bar: 45.3” x 9.6″ 
  • Individual Circular Tube Size: 16.6 cm
  • Number of Circular Tubes Included: 27

This filtration system for a 55-gallon tank offers the most discreet performance among all UGFs available in the market. Suitable for both freshwater and reef aquarium use, the Aquarium Equip Undergravel Filtration Bottom Circular Bar can be customized as per your aquarium design.

The equipment offers all the advantages of a bottom circular bar arrangement. It improves water circulation in the tank and grows highly beneficial bio-bacteria under gravel.

The unit also helps in neutralizing water temperature. The Aquarium Equip UGF provides double filtration thus allowing the tank to get optimum filtration and crystal clear water for a longer time.

The system though is a little difficult to install, and offers highly efficient and effective performance. You can use the unit with the powerhead and also connect it with the rain bar unit as well as the canister filter.

However, it cannot be connected with the standard pump, so you may need to do some make-shift arrangements to connect it with the air pump.


  • Suitable for both freshwater as well as a reef aquarium
  • Connectible with a powerhead, air filter, sponge filter, etc.
  • A completely discreet filtration system
  • Perfect for high capacity tanks
  • Highly customizable


  • Not easily connectible with air pumps
  • Tricky installation

XMHF Aquarium Fish Tank Undergravel Plastic Filter Board Air Tube


  • Aquarium Size: 55 Gallon Tank
  • Total Dimension: 13.46” x 7.91”
  • Individual Plate Size: 5.5″ x 2.8″
  • Size & Number of Circular Tubes: 28

The XMHF Aquarium Undergravel Filter is a class apart. One of the most flexible filtration systems, the XMHF filter can be connected with multiple devices including an air pump and canister filter. Besides, it can also be used with a powerhead. 

The packaging consists of 28 pieces of filters. Along with the filters, it also contains 1 lift tube,1 air hose line, and an air stone. The XMHF UGF can be used in 55 Gallon tanks. You can assemble the system according to your tank size. The filters are made with high-quality plastic.

The double filtration system cleans the water to offer a high level of clarity. The filters are extremely easy to install, simple to use, and very convenient to clean. The system offers both mechanical and biological filtration. However, the system does not contain any carbon cartridge, so it does not perform chemical filtration. For this reason, you can use it for primary filtration purposes only.


  • Can be connected with air pump, powerhead and canister filter
  • Highly flexible assembly
  • Perfect for large tanks
  • Includes air stones
  • Easy to assemble


  • Cannot perform chemical filtration

Top Pick- Penn Plax Undergravel Filter

All the top undergravel filters reviewed above have some or other unique features that make them special. Therefore, to select the best among them was not a simple task. However, by comparing all their features we could pick Penn Plax as our top pick in the category. 

The filter offers a high level of mechanical, biological, and chemical filtration for 40 Gallon tanks and 50 Gallon tanks. Besides, the filter is suitable both for the fresh water and the reef aquarium.

The Penn Plax UGF features 4 filter plates which are firmly secured under gravel. It has an adjustable lift tube allowing you to adjust as per the tank height.

It has high pore air stones which allow a steady flow of strong air for effective filtration. The filter comprises a unique Filt-A-Carb filter cartridge. Each of these cartridges offers effective chemical filtration for up to two months. Besides, the cartridges are easily available and can be replaced very easily in a quick time.

The whole filter system is also very easy to assemble and discreetly set in the tank. The highly affordable cost of filters offers true value for money to the users. High durability further enhances its cost-effectiveness.

Best Undrgravel Aquarium Filter Brands


World over, Penn-Plax is known for its passion for pets. Whether it is the aquatic species or the bird, the canines or the felines, small animals or reptiles, Penn-Plax has been serving a full line of pet categories for over six decades.

The Goldman and Rosen family, the owners of Penn-Plax, inaugurated their first pet shop in Brooklyn, New York in 1956 and have been growing steadily ever since. During this long journey of around 6½, they have received numerous patents and awards in the pet segment.

Today Penn-Plax have their production and distribution centers across more than a quarter of the nations in the world. They utilize their manufacturing facilities in producing their own brands as well as their clients’ private labels. They sell their products in all widely popular stores including .com, pet specialty, big box, and many more.

Penn-Plax has invented many innovative products including 3D aquarium background, a unique aquarium filter. It is their 3rd generation now, which is living the vision of their ancestors of offering world-class high-quality products to the pet parents.


It was almost four and a half-decade back that Lee and Mary Schultz launched the pet product company with the name Lee’s aquarium & Pet Products.

The family-owned company is now managed by their 2nd and 3rd generation. They have their office and distribution set up in San Marcos, California. Besides, they also have a big manufacturing facility in San Marcos where they manufacture around 90% of their products.

Lee’s sells its pet products including aquarium filters through around 100 authorized distributors across the country. They also distribute their high-quality products to over 35 countries outside the USA.

Apart from producing for their own brands, Lees’ also pack for many well-known private labels. They also support their clients in designing the product apart from labeling and packaging them in their production facilities.

How Does an Undergravel Filter Work?

The working of an undergravel filter is pretty simple.

  • Undergravel filter plates are placed at the bottom of the fish tank.
  • Gravel substrate is then kept over these plates.
    • This allows water to flow properly under the substrate.
  • The lift tubes of the filter are connected to the filter plates at the bottom of the aquarium.
    • These tubes then go up to the top to the desired height determined by the height of the tank.
  • The water after the filtration comes out of the lifting tubes and goes back to the tank through them.

This whole filtration system is set up before starting the aquarium. The filters can get power through either the air pumps or the powerheads.

Air Pump

Air pumps are rated as per the capacity of the tank in gallons. So, you should select the pump as per the capacity of your aquarium tank.

The working of air pumps is very easy to understand. 

  • The air pump pushes the air to the bottom end of the tube through an airline.
  • The air bubbles, thus produced, move up thereby pushing the water out along with them.
  • Water flows through the gravel substrate to the bottom of the aquarium.
    • Providing a measuring valve in the airline will be very helpful as it will indicate the correct air pressure in the system at any given time.

In the process of circulation, the air pump also adds some amount of oxygen to the water.


The capacity of the powerhead is determined by the area of the tank base in ft2. The rated capacity of the powerhead should be 60-90 Gallon per Hour per ft2. So, for a 12”x30” base size, you should get a powerhead that can pump 150-250 GPH.

The working of this system of giving power to the filters is quite similar to the air pump.

  • In this case, water is pumped up in the lift tubes.
  • The water is then pumped out of the tube to return it to the tank.
  • New water is taken in through the gravel substrate to the bottom of the aquarium. 

The water, in the case of a powerhead, will move faster. This will increase the flow of water through the gravel.

Benefits of Using an Undergravel Aquarium Filter

Undergravel aquarium filters offer many advantages particularly to those owning aquarium tanks up to 60 Gallon capacity. The following are some of the major ones that you will experience with these filters:


UGF filters are much more cost-effective than other filtration systems. These filters come in a fairly affordable price range. Besides, they do not require too much maintenance cost, as well. They are easy to clean, so do not require an expert to clean them thus saves on the recurring cost of maintenance. Moreover, the cost of replacement parts is also within the affordable range. 

Easy to set-up

There are practically no installation hick-ups in placing the filter plates in the fish tank. You just need to put the plates at the bottom and cover them with the substrate.

Installing a circulation bar filter is a little tricky but still, can be performed on your own or at most require one-time installation support in the beginning. Once set, it won’t be difficult to remove, clean, and reassemble it after cleaning.

Occupies less Space

Most of the UGF systems are pretty compact in size and flexible in the setting. You can fix them as per your tank size without occupying a lot of space.

Sitting beneath the gravel substrate, these filters are completely invisible from the outside. 

Noiseless Running

Noise can be one of the most irritating factors in an aquarium filter. UGF offers a great advantage of offering almost a silent operation thus causing no disturbance in your work and during your rest time, as well.

Getting the Best Undergravel Aquarium Filters- Buyers Guide

Buying a UGF is much easier than getting the right one. To get the right one you need to consider many factors that may impact your selection.

Here are some of the important factors which you should keep in mind when going to shop for the best UGF.

Size of the Aquarium

It is the most obvious factor to consider when selecting any type of aquarium filter. So, before shopping for the best filter, measure the dimensions of your tank and shortlist the filters that fit into that size. 

Filtration Need

Undergravel filters are primarily meant to perform mechanical and biological filtration. So, if your requirements are limited to these two filtrations, UGF is the perfect choice for you.

However, if you also want chemical filtration, you need to look for the filters that perform this type of filtration, as well. A few of the shortlisted filters offer carbon cartridges to support chemical filtration. You can select any one among them that suits your requirements.

Powerhead or Air pump

The bigger aquarium requires a powerhead to maintain proper flow and pressure in the system. The smaller ones can run effectively using an air pump only. So, you need to consider the size of the aquarium to decide between the powerhead and the air pump.


This is one of the most important factors to consider when buying a UGF. With a wide range of aquarium filters available in the market, you need to consider your budget viz a vis your requirement before selecting the most suitable one. If you have enough budget, you can go for the most feature-rich aquarium filter.

However, if you have budget constraints, you should look for the essential features in your filter and should ignore features that do not add too much functional value to your aquarium.


Many of the filter systems are so discreetly assembled in the tank that will not interfere with the aesthetics of your tank. Some filters are, however, not so discreet.

For the latter ones you need to ensure that they match with the style of your aquarium and also pleases your visual sense. Some of the not-so-discreet types actually design their filter system to enhance the aesthetics of your tank.

Type of Water

Though most of the aquarium filters are suitable for freshwater as well as saltwater, there may be some filters that may be compatible with only one of the two types.

So, you must ensure that the filter that you are buying is suitable for both types of water or at least the one that you use or intend to use in your aquarium.

Ease of Installation

There are broadly two types of undergravel aquarium filters; plate type, and circulation bar type. The plate type of filtration system is very easy to install on the bottom of the tank beneath the gravel.

On the other hand, the circulation bar type of system is a bit difficult to keep on the bottom of the tank. So, if you are using a filtration system for the first time, the plate type UGF could be the most suitable filtration system for you.

Ease of Maintenance

It is essential to clean the filters regularly as they accumulate many harmful substances over time. So, ease of removal, cleaning, and easy reassembling play a vital role in selecting an undergravel aquarium filter.

If the filter you buy requires an expert to clean it, you will have to bear the cost of getting it cleaned every time. Apart from the ease of cleaning, you also need to ensure that you get the replacement parts of the filter easily. They will help you keep your aquarium filter in perfect shape for a long time and also will ensure the good health of your fish.


Selecting a suitable undergravel filter is necessary to provide the best living environment for your pet fishes. You can use these filters in your aquarium or your breeding tank with equal effectiveness.

We hope that the reviews and other information about the best undergravel aquarium filter helped you in selecting the best one for your purpose.

If you are still not able to select the best one for your purpose, we will recommend you to go for Penn-Plax Clear Filter. With so many high-quality features, it is selected as the most useful filter on our list of best filters.

In case you are interested in buying a budget filter, Aquarium Equip ISTA Undergravel Filter will be the best option for you. And if you want to opt for a premium filtration system, we will recommend you to go with Lee’s Original Undergravel Filter.

Best Undergravel Aquarium Filters Related FAQs

Are undergravel aquarium filters efficient?

The efficiency and effectiveness of an aquarium filter are determined by its ability to provide crystal clear water that is free from any bad odor and supports its biological cleaning.

Undergravel filters fulfil all these requirements very effectively and with high efficiency. Having said that, UGFs are effective for small tanks with a capacity of up to 60 gallons. 

Is An Undergravel Filter Suitable For A Sand Aquarium?

No. Most of the standard undergravel filters are not quite suitable for sand. Sand will sink quite easily and block the filters so much so that the filters will not be able to perform at their optimum capacity.

However, you can design an undergravel system that can work with sand as is being done by many aquarists.

What is the most effective aquarium filter?

It depends upon many different factors.

Having said that, the most effective aquarium filter will be the one that provides clean and crystal clear water at all times, and is easy to use, clean, and maintain. 

Is a Canister Filter suitable to work with  Undergravel Filter?

Yes. You can very well use a canister filter with an undergravel filter. You just need to connect the undergravel filter to the inlet of the canister filter. It is particularly useful for UGFs which do not have a chemical filtration system.

What is the Most Suitable Substrate for Undergravel Filtration?

The size of the substrate determines its suitability for undergravel filtration. The thickness of the substrate should be a minimum of 2” but at the same time, it shouldn’t be too thick to lose its effectiveness of trapping particulates.

Substrate under 2” thickness will settle down and clog the filter plates thereby reducing their efficiency of filtration.

Apart from the effectiveness and efficiency of filtration, you must also consider the type of gravel from the point of view of their suitability of your fish. Coarse gravels can seriously hurt your fish while if the substrate is too fine, fish can ingest it causing internal injury or other complications detrimental to the health of your fish.

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