Best Undergravel Filter: Better Water Filtration For Your Pets

Best Undergravel Filter
Choose the best undergravel filters in our top under-gravel filtration list for better filtering for your pets. Try great filters for your sand undergravels--better for betta types, water plants and will help maintain biological balance in your aquariums.


Are you looking for a reliable undergravel filter for your tank?

Do you want a safe and efficient way to clean your aquarium without disturbing your pets?

Do you think undergravel filters would be a great addition to your tank but have no idea what the best products are in the pets market?

Although undergravel filters aren’t the most popular option on the market, they’re an alternative worth considering if you’re wanting to create personalized aquariums. Take a look at our top picks below for the best undergravel options and choose the one that suits your aquarium’s needs.

Our Choice Recommendation: Penn Plax Undergravel Filter

Penn-Plax Undergravel Aquarium Filter for 40-55 Gallon Tanks –...


The Penn Plax Undergravel Filter  is one of the best options suitable for a 40-50 gallon tank. This choice makes it easy for you to clean the water as it is composed of 4 plates that do the cleaning job. The filter mainly performs biological filtration to get rid of dirt particles and that too with no maintenance at all.

Beside dirt particles, tanks can sometimes get filled with chemicals and bad odour which can affect the health of the pets inside and also destroy the look of the aquarium. To provide solution to this problem, this best undergravel filter has 2 carbon filters whose job is to clean the chemicals found in the tank and keep the pets out of danger.

The Penn Plax Undergravel Filter also has a special function that allows you to adjust the height of the water level by adjusting the 1” jumbo lift tube in the filter.

This best undergravel filters product is extremely easy to set up in your aquarium and will give you no trouble. However, you have to buy an air pump for it and a power overhead as well if you wish to increase the amount of oxygen for your pets inside the fish tank.

Remember that this offer can break easily, so make sure you are very careful during the installation.


  • Water level can be adjusted via life tube.
  • Doesn’t affect the aesthetics of the tank as it hides from the view once covered in gravel.


  • Not very durable.

Option #2. uxcell Plastic Aquarium Undergravel Filter

uxcell Plastic Fish Tank Undergravel Filter Board Air Pump Hose...


This undergravel product  is made up of 24 assembled pieces and can easily fit in your tank. The bottom plates of this choice can be connected according to the size of the tank.

The filter set up is extremely easy and since the plastic cells are nicely crafted into tiny squared shapes, unwanted particles are easily trapped into them and the water is kept clean.

There’s a long tube and an air hose to promote good aeration in the tank. Overall, this filter is a great product that works like a charm. However, there’s one flaw in it, the filter tube isn’t much durable and might not stretch a lot in case you have a higher level of water in the tank.


  • No maintenance.
  • Easy set up.
  • Cheaper.


  • The filter tube is not of good quality and also does not stretch much.

Option #3. CORISRX Aquarium Equip Under Gravel Filter

CORISRX BEST OF YOUR LIFESTYLE Under Gravel Filter 7.8'x5.5'...


This CORISRX BEST OF YOUR LIFESTYLE Under Gravel Filter 7.8"x5.5"...  is suitable for both saltwater and freshwater tanks. There is however a limit for adding the gravel on this offer which should be around 1 to 2 inches and it also needs to be thoroughly rinsed before being added to the tank. This choice is a perfect fit for compact fish tanks where oxygenation can be a problem as the air pump is especially designed to circulate aeration throughout the fish tank. Moreover, the pipe that accompanies the filter can be easily fitted with any outer filter or submersible filter to have good filtration in the tank. The flaw of this choice is that the tube doesn’t fit properly and constantly keeps on moving which can look a bit odd to the viewer.


  • This choice is perfect for both salt and fresh water.
  • Aids in aeration.


  • Only suitable for tanks that are smaller.

Option #4. Angels Aquatics & Pet Supplies Hexagon Aquarium Fish Tank Under Gravel Filter

Angels Aquatics & Pet Supplies Hexagon Aquarium Fish Tank Under...


This Angels Aquatics & Pet Supplies Hexagon Aquarium Fish Tank Under...  can work for tanks up to 20 gallons. This best undergravel filters product comes with one uplift tube which is responsible for filtering and clearing out dirt and debris from the fish tank. There’s also an airline which you will get when you buy this best undergravel filter. The airline is an inch in size and should be connected to the end of the filter plate to stop the water from running back into the air pump. This is one of the best choices because it cleans up the toxic wastes efficiently and also helps you get rid of any harmful chemicals that may be present in the water. However, on the downside, the plastic from which this offer is made is very thin and might not support hard gravel substances.


  • Is very stylish and can improve the look of your tank. Spruce up your aquarium!
  • Is perfect for both big (up to 20 gallons) and small tanks.


  • The uplift tube is only one inch in diameter and might not flush bigger debris particle from the water.
  • Made from very thin quality plastic.

Option #5. Lee’s 40/55 Premium Undergravel Filter

Lee's 40/55 Premium Undergravel Filter, 12-Inch by 48-Inch


With this Lee's 40/55 Premium Undergravel Filter, 12-Inch by 48-Inch  you can have convenience and the ability to spruce up your tank and keep it highly maintained and free from harmful substances that may contaminate the water and affect the fish.

Just like the system discussed above, this choice also has an uplift tube that makes sure that the water is circulated properly and in all corners. The carbon cartridges in the filter clean up the bad chemicals that are formed because of pets waste and also make sure that the water doesn’t not smell.

The plates of this best undergravel filter are extremely durable and resistant to cracking, which is easily one of its best qualities as this system has a good shelf life. Moreover, the durability means you can also easily place elements like rocks and other various equipment without any fear.

However, for a 55 gallon tank, the bottom isn’t completely filled with purified water and can be a bit troublesome.


  • The air diffusers and carbon cartridges are durable and efficient in making the contents crystal clear.


  • The air stones are small and aren’t suitable for bigger tanks.

How Does An Undergravel Water Filter Work?

An undergravel filter for fish is an effective biological filter device. Two vertical “uplift” tubes are inserted into circular holes in the filter plate’s back corners. Each tube has a pump or powerhead at the top that sucks water and bubbles up through it. Water is driven down the gravel, trapping dirt and other particles, before being sucked through the filter tray’s small pores. 

What Is An Undergravel Filter?

A thick covering of gravel in your aquarium can serve as both a mechanical and biological filter, and this is essentially what an undergravel filter is made for. Simply said, an undergravel aquarium filter is a grating or plate that sits beneath the gravel substrate.

Uplift tubes are placed into the plate via a circular hole at the plate’s back corners. Water is drawn up through the uplift columns by a powerhead or pump at the top of the column, which is combined with bubbles formed by the air stone, which then drags water down through the substrate. This is essentially how they work.

Aquarium filtration with undergravel filters is a cost-effective method. With an undergravel filter, the only sound you’ll notice is the faint vibration of the air pump. When setting together an aquarium, these filters are simple to set up and are a suitable alternative to loud aquarium filters. Best of all, they don’t take up too much space either.

Consider The Following When Choosing An Undergravel Filter:

If you’re searching for an undergravel filter for your aquarium, keep the following factors in mind.

Tank Dimensions

Regardless of whether it’s an undergravel filter or not, the filter you pick for your aquarium should take the size of your tank into account. Check if the filter you’re considering is rated for your tank size and includes an integrated oxygen sensor to track how much oxygen is in the water at a given time. The larger your aquarium, the more incentive there is to utilize a powerhead rather than a regular air pump, which may not be sufficient to provide a strong enough current in your tank.

Fish Type

Loaches, for example, are not good choices for undergravel filters because they tend to burrow or dig. Your filter may become exposed frequently in a tank with fish that perform a lot of landscaping, reducing its efficiency. Under gravel filters must be buried at all times in order to perform properly and effectively.

Plant Life In Your Tank

An undergravel filter can obstruct root development and may cause your plants to suffer. A filter isn’t necessary if your tank is full with floating plants or Java ferns stuck to driftwood. Installing after you’ve already established your aquarium may upset and perhaps kill your plants if they don’t like being relocated once they’ve been placed.

What Substrate You’re Using

The name of these filters is a bit of a giveaway as to the best primary component for these filters: gravel. For the filtering process to operate, the substrate must be at least 2 inches thick; if it is too thick or thin, the filtering process will fail. Sand is frequently too fine and fills the area beneath the filter plate, reducing the filter’s capacity to suck water down through. If your substrate is too big, like rocks or large pebbles, an undergravel filter will also be ineffective. Try to find a substrate that is large enough to not fall beneath a filter plate but tiny enough to have a wide surface area. The gravel should be coarse, but not too coarse, otherwise the particles will not be trapped.

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About The Author

Joseph Bartley
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Joseph Bartley, also known as the WaterFilterFanatic, is a seasoned content writer who specializes in water filtration and water quality topics. On AllAboutWaterFilters, he has written a range of water filtration system reviews, water health and quality articles, swimming pool, hot tub and aquarium filtration guides, DIY methods to assist people clean their drinking water, and much more. Joseph enjoys spending his time working with the #AllAboutWaterFilters Editorial Team to provide some of the best quality water filtration content available on the web.

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