Best Undergravel Filter: Better Water Filtration For Your Pets


Are you sick of having to deal with murky water, odorous tanks, and sick fish? Do you want to maintain a clean, healthy aquarium without having to change the water frequently? The ideal option for any aquarium owner seeking for a dependable approach to maintain their tank is an undergravel filter. They assist give your fish a more natural environment while also offering greater filtration. You can enjoy crystal-clear water and content fish that will thrive in their new environment with a bottom filter. Additionally, these filters can survive for years with routine care! So an aquarium substrate filter is unquestionably something to take into consideration if you're seeking for a practical approach to maintain the cleanliness and health of your aquarium. Continue reading to discover additional ways that this fantastic filtration system might help your tank.


Undergravel filters are an effective and affordable way to keep aquariums clean and healthy.

  • They provide biological, chemical, and mechanical filtration.
  • They are easy to install and maintain.
  • They can be used in both freshwater and saltwater aquariums.

Undergravel is a great choice for any aquarist looking for a reliable filtration system!

Are you looking for a reliable undergravel filtration solution for your tank?

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

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

Although these types of 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

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


The Penn Plax 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 option 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 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 offer 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

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

CORISRX Under Gravel Filter 7.8'x5.5' Undergravel Filteration for...


This CORISRX Under Gravel Filter 7.8"x5.5" Undergravel Filteration for...  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

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 offer 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 option. 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

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 option 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 filtering solution 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 one of these filters 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.

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

Extra Information That Will Help Readers

With these filters, aquariums stay clean and healthy. They are an effective and efficient way to filter the water to get rid of waste, debris, and other contaminants. When choosing an undergravel option, it’s important to think about the size of the aquarium, the type of substrate, and the flow rate of the filter. How big of a filter you need to clean all the water in the aquarium will depend on how big the aquarium is. Also, different substrates need different types of filters. For example, sand needs a filter with more power than gravel. Finally, it is important to select a filter with an appropriate flow rate; too low and it won’t be able to effectively remove debris from the water, while too high can cause excessive turbulence in the tank. By knowing these important facts about these filters, fishkeepers can choose the filter that will best meet their needs and give them a satisfying experience while taking care of their fish.

Good Usage Ideas: What Can You Use Them For?

There are three main ways to use these filters: First, they can be used to filter the water to get rid of waste material and other things in it. This keeps the water clean and clear, which is important for keeping an aquarium healthy. Second, they can also be used to provide biological filtration. This means that beneficial bacteria will grow on the filter media, helping to break down ammonia and nitrites into less harmful substances. Finally, these filters can also be used as a substrate for live plants. The gravel provides an ideal environment for root growth and helps to keep the plants anchored in place. As you can probably tell, undergravel filtration solutions can quickly become an essential part of any aquarium setup.

How can you compare these products to other rival options on the market?

Undergravel options are often compared or measured against competitors in terms of their flow rate, filter capacity, size and weight, filtration level, and durability.

  • Flow rate is a measure of how much water can be filtered per minute.
  • Filter capacity is a measure of how much water the filter can process before needing to be replaced.
  • Size and weight determine how portable the filter is.
  • Filtration level indicates how much debris and bacteria it can remove from the water.
  • Durability determines how long it will last.

When comparing these filters, experts may also look at how easy they are to use, how much they cost, what customers say about them, and how much maintenance they need.

Ultimately, these performance categories provide a comprehensive overview of a filter’s capabilities and help consumers make informed decisions when selecting one for their aquariums.

What to Expect From Using It for the First Time

Using a filter like this is a great way to keep your aquarium clean and healthy. These filters are made to go under the gravel in your tank. This lets the water flow through the gravel and get cleaned as it goes. This helps remove debris, uneaten food, and other contaminants from the water, ensuring that your fish have a safe and clean environment to live in. These filters are also easy to set up and don’t need much maintenance. They are also cheaper than other types of filtration systems, which makes them a great choice for people on a budget. Overall, these filters are a good way to keep your aquarium clean and healthy that won’t break the bank.

In general, here’s how to set up one of these filters and use it: First, check that your filter is the right size for your tank. Next, place the filter plate in the bottom of your tank and cover it with gravel. Third, attach the lift tubes to the filter plate and connect them to an air pump or powerhead. Fourth, turn on the air pump or powerhead to create a current that will pull water down through the gravel and into the filter plate. Fifth, add beneficial bacteria to help break down waste in the tank. Finally, monitor your tank regularly to make sure everything is running smoothly. With these simple steps in mind, you can easily use a filter like this to keep your aquarium clean and healthy.

Consider The Following When Choosing An Undergravel Filter:

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

Tank Dimensions

Regardless of whether it’s an undergravel type of 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 options 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

A filter like this 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, the 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.

5 Expert Tips for Setting Up an Substrate Filter

  1. Choose the right size filter for your tank. Make sure it is large enough to accommodate the amount of water in your tank.
  2. Clean the gravel before adding it to the filter. This will help prevent any debris from clogging up the filter.
  3. Place the gravel filter plate at the bottom of your tank, and then add a layer of gravel on top of it.
  4. Connect an air pump to the filter plate, and make sure that all air lines are securely connected.
  5. Check regularly for any signs of clogs or blockages in the filter, and clean as needed.

ALSO: Consider adding a powerhead to your bottom filter setup to increase water circulation!</p

More Beneficial Info For Readers

Using these dependable products will help you maintain a clean, healthy aquarium at a reasonable cost. They function by pulling water through the gravel substrate, which traps trash and other particles. This enhances water clarity, lowers ammonia levels, and improves fish health conditions. Additionally, the filter offers a home for helpful bacteria to colonize, which aids in the breakdown of waste materials into less dangerous chemicals. An undergravel filter can offer years of dependable service with regular maintenance. The biggest benefit of employing an undergravel filter is how inexpensive it is in comparison to other filtration methods. It is very simple to build and maintain; all you need is a powerhead pump, a substrate made of gravel or sand, and some tubing or hoses to link everything up. Since it fits beneath the substrate layer, it doesn't take up any more room in the tank. There are a number of things to take into consideration when selecting an undergravel filter system for your aquarium, including size (to ensure it will fit).

Usage Ideas: What Are They Effective for?

These filters have three main applications. First, they are a practical means of maintaining crystal-clear aquarium water. In order to keep the aquatic life that lives inside the tank in a healthy environment, the filter functions by collecting waste at the bottom of the tank while letting oxygen-rich water to pass through it from top to bottom. In addition, these filters offer biological filtration, which is crucial for eliminating dangerous chemicals that build up over time. This could happen as a result of waste that your pets or the tank's plants produce. Finally, they can help your aquarium look more natural due of their design, which enables them to be buried beneath gravel substrate. Performance levels vs external models, such as hang-on-the-back (hob) units, are not compromised in the process. These attributes make undergravel filtration systems one of the most popular choices among aquarists looking for reliable filtration solutions.

The Disadvantages: What To Expect

After going over the advantages of these products, it's necessary to also take into account the disadvantages. In order for these filters to continue functioning, they must first undergo routine upkeep and cleaning. This can take some time because it requires taking the filter out of the tank, rinsing off any debris that has accumulated on top of the gravel, and then putting it back in. Second, these filters are best suited for aquariums with modest quantities of waste and detritus rather than all aquarium varieties. Fortunately, these drawbacks can be addressed with several doable remedies. For instance, using an automatic gravel cleaner can cut down on the amount of maintenance work that must be done manually. Additionally, other filtration systems like hang-on-back or canister filters may be a better option if an undergravel filter is not ideal for a specific tank configuration due to excessive levels of waste or debris present in the water column.

By What Criteria Should They Be Evaluated?

These dependable items are frequently judged and appraised based on their effectiveness, affordability, and simplicity of installation. Efficiency is assessed by how much dirt and other impurities the filter can remove from the water, and cost-effectiveness is established by evaluating the filter's price in relation to its effectiveness. On how fast and simply it can be set up in an aquarium, installation is rated. Additionally, the ability of these useful items to preserve a healthy habitat for aquatic life is contrasted with that of alternative filtration methods. In the end, these numerical data aid in deciding if an undergravel filter is the best choice for a specific aquarium configuration.

Overall Usage Experience: What You Need To Know

These practical items are a terrific method to maintain the cleanliness and health of your aquarium. They operate by pulling water up through the gravel at the tank's bottom, into a filter chamber, where it is filtered, and then returned to the tank. This kind of filtering system is particularly good at getting rid of trash and food scraps that can build up in the substrate. Additionally, it facilitates the growth of helpful bacteria, which aids in the breakdown of waste materials in the tank. The undergravel filter should be used in conjunction with other filtering techniques, such as chemical or mechanical filtration, for best results. It's crucial to have appropriate gravel depth when installing an undergravel filter so that water can pass freely through it without becoming obstructed or blocked. In order for oxygen to reach every part of the substrate, you'll also need to make sure that there is enough airflow around the filter plate. An undergravel filter may provide your aquarium years of dependable service with the right upkeep and care.

Generally speaking, the following is how to configure and utilize one of these filters: You'll need the right quantity of gravel for your tank to start. Make sure your filter is the appropriate size for your tank first. After that, put the filter plate in the tank's bottom and cover it with gravel. Third, connect an air pump or powerhead to the lift tubes that were attached to the filter plate. In order to pull water through the gravel and into the filter plate, create a current by turning on the air pump or powerhead in step four. Fifth, add a piece of used filter media to the tank to introduce good bacteria that will aid in the breakdown of trash. Finally, make sure everything is working well by routinely checking on your tank. You can use a filter like this to keep your aquarium clean and healthy by keeping these simple instructions in mind.

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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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