Best Undergravel Filter: What Type of Filter is Best for a Fish Tank

Maintaining substantial amounts of gravel is paramount to ensure a conducive environment for your fish as it acts as a biological and mechanical filtration medium – undergravel filter, in an aquarium set up.

Also, the undergravel filtration system plays a vital role in ensuring the flourishing of any beneficial bacteria. Now, if you are out looking for the ideal undergravel filter for your aquarium, worry not because we got you.

We are going to put together all the necessary information for you to be well informed before making a purchase as well as direct you to the top brands in the market for easier choosing. Let's discover to choose the best undergravel filter!


Best Undergravel Filter: Our Top Picks For You


Penn Plax Premium Under Gravel Filter System - for 40-55 Gallon Fish Tanks & Aquariums

4.2 of 5 Stars

Undergravel Filteration Bottom Circular Bar 33.5"X 9.6" Under Gravel Filter Tube

2.8 of 5 Stars

Lee's 115/125/150 Original Undergravel Filter, 15-Inch By 72-Inch Or 12-Inch By 84-Inch

4.6 of 5 Stars

XMHF Aquarium Fish Tank Undergravel Plastic Filter Board Air Tube 28pcs Black

4.8 of 5 Stars

What is an Undergravel Filter

At its basic level, the undergravel filtration system is merely a rectangular plate that lies under the gravel substrate in a fish tank and pulls or sucks water down through the gravel substrate. As a result, it facilitates mechanical filtration as well as providing an immensely large area for healthy bacteria to thrive.

Undergravel filter

What Are the Benefits of Using a Fish Tank Undergravel Filter

Gravel filter for fish tanks come a ton of benefits mainly when utilized in fish tanks ranging from small to mid-sized ones. We correctly recommend them for fish tanks that are under 55 gallons. There are however seasoned aquarists who are comfortable using them in larger fish tanks set-ups.

Now, if you are considering pimping your fish tank with an underwater gravel filter, here are the benefits you are likely to enjoy: 

Cost-effectiveness: unlike what you would think, undergravel filter setups are generally affordable compared to other types of aquarium filters in the market today.

Elaborate set-up: these fish tan filters are easily set-up, especially when assembling your aquarium. You only need to place the filter plate at the bottom, place the substrate and you are pretty much done.

Saves space: aside from the additional equipment that could be used alongside it like air tubes, air pump and powerhead, the undergravel filtration system saves a lot of space as it sits under the gravel substrate.

Quiet: undergravel, filters are also environment-friendly as the only noise they give is the subtle vibration of the air pump. If you find other fish tank filtration systems noisy, then this might be just what you need.

With these benefits in mind, let us take you through:

How Does an Undergravel Filter Work

The principle under which these filters operate is rather simple - The water in the fish tank is forced down the available gravel. It facilitates the trapping of debris and any other dirt particles in the aquarium. The clean water is then sucked through some tiny holes on the filter tray and forced back into the tank through an uplift tube.

Undergravel filters are not only limited to fish tanks but can also be used in larger spaces such as fish ponds. In a pond situation, however, you will need a powerhead producing enough current to force water down the gravel. This, as earlier stated, makes the gravel a biological and mechanical filtration media that also allows for the growth of healthy bacteria colonies.

Read more:  Best Hang On Back Filter: Top Choice From 70 to 110 Gallon Fish Tank

However, that regular siphoning to keep the gravel clean is a crucial undergravel filter fish bowl maintenance measure. Ensure that you are conversant with the steps for effective maintenance. Undergravel filter with canister filter is widely used.

Now that you have a sneak peek at how these filters work, let us take you through; 

How to Choose the Best Undergravel Filter: Factors to Consider

Tank size: while this is universal for all filtration systems, taking into consideration the size of your tank before purchasing an undergravel filtration set up is paramount. Counter check whether the undergravel filter you want to buy is rated for your aquarium size.

Filtration type:  this should be specific to your aquarium type. Some tanks only call for biological and mechanical filtrations. If this is the case with your fish tanks, then the undergravel filter is more than enough for you. On the other hand, if it calls for chemical filtration in addition to these different two types of filtration, then you should not be content using only the undergravel filter. Instead, use it secondary to the primary chemical filtration.

Auxiliary components:   like we earlier mentioned, some Undergravel filters come with extra elements such as air pumps while others call for the use of powerheads. That is, a bigger aquarium will call for a powerhead as opposed to the pure air pump. A powerhead will provide more current hence more power to move more water along in the tank.

Your budget: this is a factor we all too well ignore. Knowing your budget is a top factor to consider. With the wide variety of filters in the market, you can get the right filter for your need at a bargain. Setting a budget will help you know what range of filters are within your reach. It makes it easier to choose something that works for you without having to eat into your finances overly.

Personal preference: we can all agree that style is crucial as it speaks volumes about us. You want to get yourself something that will not make you want to wreck the tank every time you look at it. There is a wide array of filters in the market. You can get a round undergravel filter or any shape that blends well with your fishbowl. Unless your preferences alter the filter's functionality, always go for something that compliments who you are.

Maintenance: filters accumulate dirt and debris over time, which can be harmful to your fish if not timely removed. Consider choosing an undergravel filter that you can easily uninstall and clean. This way, you will not have to incur any maintenance cost each time you remove your filter for cleaning. Getting a filter with readily available spare parts is also advantageous. Undergravel filter replacement parts are everywhere.

How to Safely Set Up an Undergravel Filter in Your Fish Tank

How to use an undergravel filter is one of the most common questions. However, once you know how to set this filter correctly, you will be ready to use the filter without further guidance. We will be sharing with you two best methods you can apply to set your undergravel filter. Feel free to experiment when you feel creative

Method 1: The Sand Cap – Undergravel Filter With Sand

This setup idea combines the efficiency of the undergravel filtration system with the benefits that sand brings to the table – that is, it does not trap gravel. The recommended sand for this setup method is the CaribSea aquarium sand. Of all the sands, it has the best outcome.

Here is why; the size of its grains is relatively larger than the average sand but still small enough hence preventing fish from choking debris sits on it awaiting cleaning.

Another advantage with this method is that you do not have to deal with the stress of plant roots in the filter plates due to the placement of the poly fiber barrier. This method, however, is conducive for rooting plants.

We recommend the addition of heavily rooting plants to keep the substrate aerated while locking down the gravel under the sand when fish dig. Since the barrier is not thick enough to function as mechanical filtration, the replacement does not have to be continual. It works well with fish tanks with plants.

Read more:  Little Known Ways to How To Lower/ Raise Ph In Aquarium Naturally

How to Set Up:

Place the assembled undergravel filter plates on the bare and clean bottom of your fish tank. In case you have already set-up your tank, consider thoroughly vacuuming and changing the water. Use airline tubing and an air pump to run the air stones in the filter. Cut a thin piece of poly fiber padding to fit the surface of the plates.

It ensures no fine sand or debris penetrates below the plate and become unpleasant over time. Ensure you snip a slit where the Undergravel uplift tubes connect. It allows enough water to flow while preventing dirt from penetrating.

Pour a half to an inch of gravel or crushed coral. It helps with the circulation of water as well as an additional surface for biological colonize. You could also choose to add mesh to prevent mingling with the sand.

Pour one and a half to two inches of sand over the gravel. In case you keep digging fish, go for two inches to ensure the gravel underneath is not disturbed.

Method 2: The Reverse Flow Method

Reverse flow undergravel filter setup has massive advantages. Here are simple steps that you can follow to set up your filter.

How to Set Up:

Place your assembled undergravel filter plates on a clean and bare fish tank bottom.
Pour a layer of gravel.

Use a submersible powerhead to force the down the uptake tubes. Doing this reverses the flow by pushing the water up the substrate rather than forcing the waste down.

Install a pre-filter on your powerhead. It prevents debris from being pushed by the powerhead below the filter plates.

By opting for either of these set-ups, you allow your undergravel filter to fall into the Eheim Undergravel filter category.

Best Undergravel Filter Review

We know the headache that comes with trying to get the best undergravel filter. We have put together a list of the best undergravel filter in the market considering price, efficiency, style, ease of use and longevity.

1. Penn Plax Premium Under Gravel Filter System - for 40-55 Gallon Fish Tanks & Aquariums


Over the years Penn Plax has been delivering high-quality aquarium accessories, and their undergravel filter is no different. If you are looking for an undergravel filter for 40 to 50-gallon fish tanks, then you might want to consider Penn Plax undergravel filter. It is flexible since you can use it in both freshwater and marine aquariums.

This filter has a simple design to ensure easy replacement of accessories and installation. The design also allows the filter to stay out of sight. This can be very suitable for people who don’t like seeing the filters in their aquariums.

One thing that sets the Penn Plax undergravel filter apart from other undergravel filters is the chemical filtration section. It has two carbon block cartridges to deal with pollutants, discoloration and odor. The Penn Plax carbon cartridges are easy to find in the market when you need to replace them.

The Penn Plax undergravel filter has four filter plates and comes with one-inch adjustable rise tube. The kit also includes clips for holding each section. This allows placing your filter firmly under gravel.




Overall rating :  4 / 5


  • Suitable large aquariums – 40 to 50 gallons.
  •  It has an easy setup.
  • It includes chemical filtration. 


  • The tube pieces included are thin hence fragile.

2. undergravel filteration Bottom circular Bar 33.5"x 9.6" Under Gravel Filter Tube


The Aquarium Equip Undergravel Filtration Bottom Circular Bar is the true definition of discreetness. The filter’s design allows it to be hidden in your aquarium fully. It works in both freshwater and marine fish tanks of up to 55 gallons. So, you don’t need to change your filter if you decide to change your type of aquarium.

While its installation is a bit complex, it is the best fit for a person who is looking to set up a customized aquarium. So, you might find this undergravel filter to be suitable if your aquarium shape is more artistic.

It can also function alongside a canister filter by merely connecting it to the canister filter’s inlet, or you can also employ the powerhead. It, however, does not attach to the standard air pump tubing.

Read more:  How Often To Clean Canister Filter: Simple (But Important) Things You Need To Know




Overall rating :  4 / 5


  • Can be used with a canister filter. 
  • It is a rather discreet undergravel filter.
  • Can be used in both salt and freshwater tanks.
  • Can be easily customized. 


  • It has a complicated installation process.
  • Not readily compatible with air pumps. – go for a powerhead 

3. Lee's 115/125/150 Original Undergravel Filter, 15-Inch by 72-Inch or 12-Inch by 84-Inch


The Lee’s Original Undergravel Filter comes with a multi-level plate design that does not crack or split because it constitutes of resistant plastic. It can, therefore, support the weight of your gravel substrate comfortably in addition to the water column. This undergravel filter also eliminates chemical wastes with its active carbon cartridges.

It comes with four riser tubes and two bottom plates. It can also function with a powerhead, an aerator, canister filter inlet or amazingly, all of them at a go. The plate design allows them to fit a 48-inch long aquarium and used in tanks of 55 – 60 gallons. It is also ideal in both saltwater and freshwater aquariums.

It also offers chemical filtration in addition to the mechanical and biological filtration setups. 




Overall rating :  4 / 5


  • It has high-quality material. 
  • Does not crack. 
  • It has multiple tube ports.
  • Has activated carbon cartridges to facilitate chemical filtration. 


  • Filter tubes re somewhat small.

4. XMHF Aquarium Fish Tank Undergravel Plastic Filter Board Air Tube 28pcs Black


XMHF Aquarium Fish Tank Undergravel Plastic Filter is at the bottom of the list, but it’s still a very good filter. Its material and design make it easy to clean and long-lasting. The beauty of this undergravel filter is its double filtration system.

The double filtration ensures that your aquarium water remains crystal clear and healthy for your aquatic life. This filter is composed of 7 layers and 28 small pieces that make up the filter board.

The XMHF Aquarium Fish Tank Undergravel Plastic Filter kit comes with an air stone. This filter needs a water pump or air pump to be able to function effectively




Overall rating :  4 / 5


  • The filter comes with a double filtration system.
  • The filter’s material is durable.
  •  It’s easy to clean and install. 


  • It needs water pump, canister, or an air pump to function effectively.

Q&A: Best Undergravel Filter

Are undergravel filters effective?

Effective filters are rated by their abilities to eliminate odor, keep water clear, and strong biological filter growth. Undergravel filters meet all these cuts, so it’s safe to say they are effective. However, undergravel filters are only effective to small gallons. Nothing over 55 gallons.

Can you use sand with an undergravel filter?

No. Sand can easily sink and clog your undergravel filter. You want your filter clear so that it can perform in optimal levels. However, there are aquarist enthusiasts that DIY undergravel filters for sand aquariums. These undergravel filter with sand resistant features also works pretty well.

What is the best aquarium filter?

The answers are so many. However, the best aquarium filter is one that is user-friendly, easy to clean and install, and eliminates all the waste in your aquarium, including odor and undesirable watercolor.


With this comprehensive review on undergravel filter, we are satisfied that you are now empowered to pick the best undergravel filter for your aquarium to keep the fish environment clean and healthy. You can have undergravel filter planted tank and not worry about the filter sucking in your plants.

With these, you have a choice from whichever price range your budget lies, not forgetting style. As you can see, you have numerous options. Also, it’s important to note that undergravel filter replacement parts are easily accessible in the market.


Related keywords: under gravel filtration, undergravel aquarium filter, undergravel filter vs power filter, under gravel fish tank filter, undergravel filter for fish bowl, 10 gallon undergravel filter, undergravel filter 55 gallon, best undergravel filter system

This post contains affiliate links. For more information, visit my disclosure page.

0/5 (0 Reviews)

Leave a Comment