Product Reviews, Aquarium Filters

The Best Internal Aquarium Filters: Fully Submersible and Underwater

Internal aquarium filters can be hidden under a rock, wood, or decoration. Providing you with a clear view of the whole tank without being noticed.

best internal aquarium filters

Internal aquarium filters (also called underwater or submersible filters) are the best way to keep your tank clean. These types of filters sit inside the tank and work by pumping water through a filter media that traps particles, dirt, and debris. There are many different models on the market today, so it can be hard to pick the best internal aquarium filters or know which is right for you – but we have done all of the research for you!

In this article, we will go over some of our favorite submersible aquarium filters, cover how they work, and answer some commonly asked questions about them.

  1. Best Underwater: Fluval Underwater Filter
  2. Best for Turtle Tank: Aqueon Quietflow Internal Power Filter
  3. Best Budget: Aqueon QuietFlow E Small Internal Filter 
  4. Best Canister: MarineLand Magnum Canister Filter
  5. Best Silent: Penn-Plax Cascade 600 Submersible Aquarium Filter
  6. Best for Large Aquariums: Tetra Whisper Internal Filter
  7. Best for Nano Aquariums: Marina I25 Internal Filter

Best Internal Aquarium Filters Reviewed

We have spent days researching the best internal aquarium filters to bring out the best ones on the market. Even that every sponge filter can be fully submersible we haven’t included any of them. That’s because they don’t provide enough power and flow rate to handle large tanks.

Below we have reviewed different filters and highlighted their specification pros and cons so that you can make the best decision for your tank.

Best Underwater
The Best Internal Aquarium Filters: Fluval Underwater Filter
Photo: Amazon.com

The Fluval Underwater Filter is the perfect solution to all your aquarium needs. This filter is great for both beginners and experienced aquarists alike, as it is easy to use and maintains a high flow rate. Its compact design fits into any corner of your tank.

This filter also comes with many features that make it stand out from the competition, such as an adjustable 3-way flow control that allows you to customize the type of flow and direction of circulation for your tank. It also has a noise-dampening feature that ensures your tank remains quiet while the filter is running. With the convenient flip-top lid, you can easily access the cartridge when it’s time to replace or clean it out! 

Products Specs

  • Flow rate: 260 GPH
  • Aquarium capacity: 65 gallons (available in different models)
  • Media capacity: Medium
  • Free media included: Foam filter pad, poly/carbon pads, biomax

Pros

  • Quick flip tip maintenance
  • Adjustable 3 way flow (top,middle,bottom)
  • Versatile positioning (vertically, horizontally)
  • Silent operation
  • Dependable

Cons

  • The knob comes off easily

Get it on Amazon, or at Chewy

Best for Turtle Tank
The Best Internal Aquarium Filters: Aqueon Quietflow Internal Power Filter
Photo: Amazon.com

The Aqueon Quietflow Internal Power Filter is perfect for turtle tanks as it comes with a specially designed filter cartridge that helps to remove heavy debris and waste. This filter also has a unique waterfall feature that creates a simulated natural environment for your turtles.

The Aqueon Quietflow Internal Power Filter has four-stage filtration so that it will rid your tank of debris, toxins, odors, ammonia, and nitrates. It also has higher flow rates for proper turnover. You won’t have to prime the pump at setup or after cleaning because the submerged pump starts automatically after power interruption. And best of all, this filter is super silent!

Products Specs

  • Flow rate: 155 GPH
  • Aquarium capacity: 30-40 gallons (available in different models)
  • Media capacity: Medium
  • Free media included: Activated carbon, BioGrid

Pros

  • Fully adjustable return flow rate
  • No priming at setup
  • Waterfall design
  • Vertical or horizontal mounting
  • Easy to use your own media

Cons

  • Not recommended for Bettas

Best Budget
The Best Internal Aquarium Filters: Aqueon QuietFlow E Small Internal Filter
Photo: Amazon.com

Aqueon is back on our list with this Best Budget Internal Filter, the QuietFlow E Small. This filter has an adjustable flow rate that allows you to choose between normal or high current for your tank setup. It also uses a unique waterfall feature in combination with activated carbon so it can remove odors and toxins from your aquarium water.

The Aqueon Quietflow comes complete with all of its cartridges which means no assembly is required! It’s super versatile as well — you can use it inside tanks up to 40 gallons large! The best part? You don”t have to prime the pump when setting up or cleaning – just plug into any standard outlet and let the submersed pump start automatically after power interruption.

Products Specs

  • Flow rate: 130 GPH
  • Aquarium capacity: 20 gallons (available in different models)
  • Media capacity: Medium
  • Free media included: Coarse media sponge, bioholster, carbon

Pros

  • Auto-start pump
  • Easy to install
  • Affordable
  • It runs on small replaceable filters

Cons

  • Suction cups aren’t the best

Get it on Amazon, or at Chewy

Best Canister
The Best Internal Aquarium Filters: MarineLand Magnum Polishing Internal Canister Filter
Photo: Chewy.com

The Magnum Polishing Internal Canister Filter is the perfect filter for your large aquarium. It has two chambers that can hold carbon, and it comes with free media. Its quick and easy cartridge change system ensures you don’t have any downtime when it comes time to clean or replace the filter media.

With one submerged motor, two refillable chambers, three stages of filtration (or polishing with micron cartridge), powerful flow rate – this filter has everything you need to keep your tank healthy! The housing material is also corrosion-resistant so that it won’t crack over time like some less expensive options out there!

Products Specs

  • Flow rate: 290 GPH
  • Aquarium capacity: 97 gallons
  • Media capacity: Extra large
  • Free media included: Black Diamond Premium Activated Carbon and Marineland Rite-Size JH Floss Sleeve

Pros

  • Dual chamber media container can hold your filter media
  • No back flush
  • Quick and easy startup
  • High-efficiency polishing (with micron cartridge)

Cons

  • Not recommended for small tanks

Get it on Amazon, or at Chewy

Best Silent
The Best Internal Aquarium Filters: Penn-Plax Cascade 600 Submersible Aquarium Filter
Photo: Amazon.com

If you are looking for an internal filter that is super silent, then the Penn-Plax Cascade 600 Submersible Aquarium Filter might be what you need. This filter has an adjustable and directional water flow and comes complete with all cartridges needed to get started! Plus, it also has a sponge to promote colonies of beneficial bacteria.

This submersible pump can fit into any small or large tank setup without taking up valuable space with its unique design. Best of all, it’s easy to install – just attach hoses and place them in the desired location inside your aquarium! This filter also includes a large filter cup for any choice of filter medium – just pick what works best for you!

Products Specs

  • Flow rate: 175 GPH
  • Aquarium capacity: 50 gallons (available in different models)
  • Media capacity: Large
  • Free media included: Activated carbon, Bio-sponge

Pros

  • Adjustable and directional flow
  • Elbow attaches pump to spray bar
  • Powerful and quiet
  • Good bang for the buck

Cons

  • A hole underneath the filter can kill small fish

Get it on Amazon, or at Chewy

Best for Large Aquariums
The Best Internal Aquarium Filters: Tetra Whisper Internal Filter
Photo: Chewy.com

The Tetra Whisper Internal Filter is the best internal aquarium filter for large tanks. This filter has a unique dual-sided Bio-Bag mesh that helps to break down harmful waste and toxins in your tank water. The Tetra Whisper also has an adjustable flow rate, so you can customize it to fit the needs of your aquarium!

It’s a submersible filter with a quiet, convenient, 3-stage filtration system—chemical, biological and mechanical. Anti-clog design for convenient and easy maintenance is also provided by the bio-scrubber. Best of all, this filter is great for the price!

Products Specs

  • Flow rate: 170 GPH
  • Aquarium capacity: 40 gallons (available in different models)
  • Media capacity: Large
  • Free media included: Whisper bio-bags

Pros

  • Dual-sided Bio-Bag mesh
  • Anti-clog design
  • Flexibility to add any media
  • Two ways of hanging the filter suction cups, and designed bracket
  • Waterfall design

Cons

  • No adjustments for flow
  • It feels more like a HOB filter

Get it on Amazon, or at Chewy

Best for Nano Aquariums
The Best Internal Aquarium Filters: Marina I25 Internal Filter
Photo: Amazon.com

The Marina I25 Internal Filter is a great internal filter for nano aquariums. It has an adjustable flow rate to ensure optimal water movement at all times! This filter comes complete with cartridges and media needed, so no need for extra media. Unless you want to personalize it with your filter media.

With its suction cup feet, it can be placed anywhere in your tank without worrying about cords or electrical outlets. Suitable for use even on the smallest nano tanks up to 7 gallons large! This filter is not too expensive yet doesn’t sacrifice quality – making it a perfect match if you don’t have much room in your budget but are looking for something that will keep your fish healthy!

Products Specs

  • Flow rate: 40 GPH
  • Aquarium capacity: 6.6 gallons
  • Media capacity: Small
  • Free media included: Mechanical, biological, and chemical media

Pros

  • Waterfall spout for oxygenation
  • Silent operation
  • Ideal for Betta fish
  • Super small size
  • Worth the price

Cons

  • There is no top of it. The filter pads are exposed
  • It can not be 100% submerged

How it Works

Internal fish tank filters are placed inside the tank and work by sucking up water from the bottom of the tank and pushing it through a filter media. This media can be anything from activated carbon to biological filters, which help break down ammonia and nitrite – two harmful toxins that fish produce.

Most submersible aquarium filters also come with an intake tube that can be attached to an air pump, which allows the filter to suck up debris and waste from the water even more efficiently.

best internal aquarium filters

What to Consider When Buying the Best Submersible Aquarium Filters

When shopping for the right underwater aquarium filter to add to your fish tank, consider a few important factors, including the flow rate, price, and noise Ahead, find out more about the key attributes of these mini fish tank filters.

Flow Rate

The flow rate of an internal aquarium filter refers to how much water it can pump through the media per hour. This number is important because you want a filter that will be able to keep up with the amount of waste your fish produce.

If the flow rate is too low, then the filter won’t be able to keep up with the amount of waste produced by your fish and will become clogged quickly. Conversely, if the flow rate is too high, it can cause a lot of noise and disturbance in the tank.

Price

Aquarium internal filters vary in price, with some costing as little as $20 and others priced over $100. While the cost of internal aquarium filters varies, they are generally cheaper than external filters.

Although some filters may be cheap, they aren’t very good at cleaning out debris and waste from water. If you care about the health of your fish, then it’s essential to have a powerful filter. Getting the best underwater filter is a purchase of a lifetime, therefore we recommend you invest in the top one.

Noise

Internal filters are typically fairly quiet due to the fact that they sit inside your fish tank. However, some cheaper models can cause noise in the tank because their motor isn’t properly insulated or is too powerful for the pump size.

If you are going to place your tank in a bedroom and you are sensitive to noise, then it’s important that you choose the quietest aquarium filter. To help this process along, we have included the best quietest models of internal filters on our list below.

Our Verdict 

The best overall internal aquarium filter is the Fluval Underwater Filter, and it’s no surprise why! This filter has multiple chambers for various types of filtration media, an adjustable three ways-flow, an easy cartridge change system, and housing that won’t crack or corrode.

If you want more space for your filter media, the MarineLand Magnum Polishing Internal Canister Filter has just that. This canister filter offers two refillable chambers for your filter media along with carbon pre-filters and sponges to promote healthy colonies of beneficial bacteria.

How we Choose the Best Aquarium Filters 

When it comes to choosing the best internal aquarium filter, we looked at a few different factors. This included an adjustable flow rate for optimal water movement, durability, and price point. We also wanted to provide filters that had sufficient space for various types of media- whether you want mechanical or biological filtration, this article has the best options available!

We have thoroughly tested each internal filter on our list – so you can be sure that they are quality products! We highly recommend all of the small aquarium filters on this list – they are all top quality for a great price!

best underwater aquarium filters

How To Set Up An Internal Aquarium Filter

Once you have chosen the best aquarium filters for your needs, it’s time to set it up! All of the filters on our list are easy to install, but we will provide general instructions just in case.

  1. First, remove all packaging and take out the filter. Check to ensure that everything is included and in good condition before moving on.
  2. Second, find a spot in your tank for the filter. This could be anywhere – as long as there is an electrical outlet nearby!
  3. Attach the hoses to the filter and then plug them into the nearest outlet.
  4. Finally, turn on your filter and adjust the flow rate according to your preference. You’re ready to go!

Best Position to Place your Underwater Aquarium Filter

The best position for internal aquarium filters usually depends on the type of substrate that is used in the tank. If you have a lot of gravel or other small particles in your substrate, then it might be better to place the filter near the bottom and back of the tank so that the water will be cycled through all of the substrates. 

If you have a more sand-based substrate, then it might be better to place the filter nearer to the top of the tank so that it doesn’t disturb settled sand.

FAQs

The above information was designed to give comprehensive information about the important aspects of choosing an aquarium filter. We have also provided information on top brands to help with the selection. We found a few areas that understandably cause concern during our research, so we have provided answers below.

Q: Are internal fish tank filters any good?

Yes! If you are looking for an easy-to-maintain filtration system, then internal fish tank filters are definitely the way to go. They can be easily hidden in your aquarium, and they provide a reliable source of water movement that will keep your fish healthy.

One of the best internal aquarium filters is the Fluval Underwater Filter. It is a great filter that comes with three types of filtration media, adjustable flow rate, and an easy cartridge change system to ensure optimal health for your fish!

Q: Are external aquarium filters better than internal?

External aquarium filters are definitely better than internal aquarium filters – but that doesn’t mean that internal filters are bad! External aquarium filters provide more space for media and they are easier to clean. However, they can be difficult to install, and they can take up a lot of room in your tank.

Internal aquarium filters usually have a smaller footprint, and they are easier to hide. They also tend to be less expensive than external aquarium filters. So, it really depends on your needs as to which type of filter is better for you!

Q: Where should I place my internal filter?

You can place your internal filter anywhere in your aquarium, the best is near the substrate. It is recommended to have the pump on one side of your tank so that it has good water flow throughout the entire system. Your best bet would be to find a quiet spot for the filter away from any heaters or light fixtures.

Choosing an underwater aquarium filter with suction cup feet like Marina I25 Internal Filter can help keep it in place, but if you are using a filter with hoses, make sure there is plenty of slack so that the hoses do not kink.

Q: Do internal filters go under the water?

Yes, internal aquarium filters are submerged in the water – hence the name “internal” aquarium filter! This is what separates them from external filters, which sit outside of the tank. They usually come with a suction cup base (like the Marina I25 Internal Filter model), but they can be placed anywhere in your tank, including on top of rocks or decorations. Best of all, they are very easy to hide!

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I am Mario, a expert aquarist who is sharing his knowledge with everyone.

Keeping innocent fish and aquatic plants safe and healthy is my daily routine. With my experience and my passion for aquatic life, I will advise you through the long run of keeping an aquarium.

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