Internal Aquarium Filter: Buyer’s Guide

aquarium internal filter

Choosing the right internal aquarium filter for your sea creatures, whether it’s saltwater, brackish water, or freshwater, is a crucial part of setting up a new aquarium or enhancing an existing one. That’s why we’ve compared and contrasted some of the most popular aquarium internal filters on the market in order to provide the best recommendation for your tank.

For this compilation, we researched and evaluated specific internal aquarium filters. Those that you can position inside your tank. We have not considered external filters, so those that you can install under, above, or connect to the rim of an aquarium tank.

Making the best choice essentially comes down to a few crucial factors, such as tank size, fish supply, and setup. Some tanks will require a high-powered, complete filter, whilst a simple betta tank may only require basic filtration. Bigger does not always mean better!

What Is The Function Of An Internal Aquarium Filter?

Internal filters are a great choice for small to medium-sized aquariums. Besides the water pump, they are highly important components of most aquariums. They are simple to mount and sit simply within the aquarium. Allowing them to readily fit into any fish tank without the use of cumbersome pipes and lines. You may also use them as a powerhead for water movement, with the added benefit of further filtration. 

Internal filters are the most simple and generally available sort of aquarium filter, and they’re ideal if you don’t have enough space around your aquarium for additional equipment. The output of an internal filter lies just below the water’s surface and rests on the border of your fish tank. The filter sucks the water inside and then strains it via filter material before returning it to your tank.

It’s necessary to keep in mind that you should clean the impeller of your filter every few weeks to ensure that it’s operating correctly and that water is moving in the tank.

The Basics Of Internal Aquarium Filter

aquarium internal filters
Photo by Vikram Mudaliar on Unsplash

Every filter should clean the water and transform dangerous ammonia into less hazardous chemicals. Mechanical filtration is the process of trapping trash, whereas biological filtration is the process of transforming waste using microorganisms. You can use chemical filtration when you want to absorb or change anything in the water.

The finest filters integrate mechanical, biological, and chemical filtration, however, basic foam filters may filter mechanically and biologically using only a sponge. Small tanks obviously require smaller filters. Whereas large tanks require much larger filters to deal with large troublesome fish. The bigger the filter output and media capacity, the larger the tank so you can support more fish inside.

Internal Aquarium Filter Is The Easiest To Operate

You can position internal filters inside the tank and drive it by an air pump or by a powerhead or pump. They are easy to use and install. They are also compact, making them ideal for small tanks. Furthermore, they are inexpensive to run. Air-powered sponge filters are required for aquariums housing fish fry. Because they provide gentle filtering without sucking up the newborn fish. Internal power filters, which generate a jet of water and draw in more trash, are the most widely used form of filter.

Choose a modest internal power filter for a small tank and a larger model for a large aquarium, or double up and have one at either end of the tank. You may also vary cleaning to maintain good bacteria levels high and allow them to function correctly.

Frequently Asked Questions

Source: Gurribuy

What Are The Benefits Of Purchasing An Internal Aquarium Filter?

Internal aquarium filters take up less space and cost less than external filters. Besides filter refills, they are quite simple to set up and seldom require any additional components.

What Are The Different Types Of Internal Aquarium Filters?

The most notable variation in the internal aquarium filter spectrum is between different filter materials and filtration procedures. Different filter materials are better suited to different waste categories. As they allow particles of differing sizes to pass through. Some filters are solely designed for freshwater or marine aquariums. While others can handle both. This is generally indicated in the product specifications.

What should You consider?

It’s vital to double-check that your filter is compatible with your tank. First, ensure your filter is suitable for the type of water in your tank; a freshwater-only filter might be detrimental to a marine aquarium. Since a filter can only take so much water, you need also look at the amount of water it can process. Most filters have a recommended upper and lower tank size limit to help you figure this out.

Our Standards (How These Filters Made The Cut)

Before we review different filters let’s speak about the parameters we used to choose these filters. When compiling this list, we considered the following:

  • Features – We’d want a three-stage filter or any other distinguishing feature.
  • Brand Name – Everything on this site is a brand name, reliable, and backed by a long warranty.
  • Ease of Use – We’re looking for something that’s ready to use and maintain. Nobody loves an overly complex filter. It’s all about simplicity when it comes to internal filters!

OASE BioPlus Internal Aquarium Filter

This three-stage internal aquarium filter is driven by filter foam and active carbon foam. You may also add a polishing stage by replacing one of the foam filters with a 30 PPI fine foam. When you change the media, the filter might continue functioning.

The outlets are intended to sweep the surface of the aquarium to reduce surface scum buildup and include an adjustable dial to control the flow rate.

An OASE Heat Up aquarium heater can be installed on the rear of the filter. This keeps the heater hidden and away from your fish. This feature contributes to a tidy display. It is meant to fit into a corner and remain hidden!


  • There is an incorporated heater in the compact filter design.
  • Includes biological, mechanical, and chemical filtering in three stages.
  • The internal corner filter softly circulates and filters aquarium water.
  • The filter has a diffuser and an adjustable water flow nozzle for consistent surface circulation and increased dissolved oxygen.


  • Built-in heater
  • The mechanical filter chamber is detachable.
  • Long-lasting – German-made


  • Costly
  • It’s hard to locate in local fish stores.

Penn-Plax Cascade Internal Filter

Penn-Plax has one of the most efficient filters. This filter is intended to be used as an internal canister filter. It can carry a lot of material for an internal filter and is entirely contained, so you can put anything you want in each compartment.

It is meant to be a submersible filter that may be installed either vertically or horizontally. This makes it an excellent choice for use in shallow aquariums, paludariums, and turtle tanks. It also has a direction flow nozzle, allowing you to control the flow in whichever direction you wish. This filter is more versatile than the BioPlus, which is built specifically as a fish tank filter.

The filter can also employ a venturi outlet or spray bar to supply oxygen to your water. The Cascade includes a flow regulator on the top of the unit that allows you to control the flow of the outlet. The filter is simple to use and reasonably priced.

It doesn’t have the most appealing appearance, but it is the most flexible filter on our review list. If you’re looking for the best value for your money, this is without a doubt the finest deal.


  • Quiet & efficient
  • Accommodating: the adjustable flow switch lets you adjust the flow of water at any time.
  • Fully submersible
  • Venturi aeration
  • Aerating spray bar


  • 3 stage
  • Large capacity
  • Great price


  • Ugly looking
  • Large profile

Tetra Whisper Internal Filter

The whisper filter contains the conventional “bio-bag,” but it also features a permanent biological filter (called a bio-scrubber by Tetra) that compensates for the detachable filter cartridge. It is very quiet and simple to operate.

The Whisper In-Tank Filter provides the same reliability and productivity as an external filter while operating in as little as 2 inches of water, making it perfect for turtle tanks or generating a waterfall inside the tank. With fitting suction cups and/or a frame, the Whisper In-Tank filter effortlessly adapts to high or low water levels. Each filter includes one Whisper Bio-Bag filter cartridge that has been pre-assembled.


  • Universal design. The Tetra Whisper 20i internal filter combines an air pump and a water filter into one unit. 
  • Internal filter. Mounts to the interior of your aquarium  with a clip 
  • Catches debris.  Filters dirt and fish waste with a dense dual-sided mesh. 
  • Aerates water. The air-driven technology filters up to 125 gph while aerating the water. 
  • Convenient design. Filter mounts within the aquarium using big, easy-to-change biobag cartridges, allowing the tank to be placed flush against the wall.


  • 3 stage
  • Cheap
  • Air-driven


  • Cartridge based
  • Can only mount with a clip

Marineland Magnum Polishing Filter

When working normally, the filter is a two-stage filter. It features a media chamber and a filter fiber sleeve that slides into the chamber. If you intend to use this as a three-stage filter, fill the media chamber with a biological filtering medium. It has a splitter in it, so you can put more than one sort of media in it.


  • Internal canister filter:
  • Versatile filtration: 
  • Micron water polishing:
  • Included components: Marineland magnum polishing internal canister filter (ml90770)


  • Powerful
  • Diatom option
  • Works up to 90 gallons


  • Only 2 stage
  • Large

Aqueon Quietflow Internal Filter

Finding a filter that works with freshwater prawns and fish fry may be difficult! Sponge filters work, but there is a need for a more thorough filter that deals with these little animals.

This need is addressed by the Aqueon Quietflow internal aquarium filter. It truly does a decent job of meeting the demand. It has a three-stage filtration system. Chemical is handled by a filter cartridge system, while mechanical is handled by a coarse sponge. It has a  Bioholster, a plastic grid that is designed to harbor beneficial microorganisms.


  • Self-Priming for a Quick Start
  • For biological filtration, a small carbon cartridge, a media sponge, and a Bio-Grid are included.
  • Aqueon Small Replaceable Filter Cartridge is used.
  • For use with aquariums up to 10 gallons.


  • Works for shrimp and fish fry
  • Easy to operate
  • Comes in 10 or 20-gallon size


  • Cartridge based
  • Noisy

Fluval U3

The Fluval U3 is, without a doubt, the most powerful internal filter on our review list. This is an internal filter that is designed similarly to Fluval’s C3 series filters. It features a thorough three-stage mechanism. The model uses two foam pads, one for mechanical and the other for polishing. Also, it features two chemical filtration cartridges and two ceramic rings for biological filtration material.

Just like the Penn-Plex, it is a submersible filter that may be installed horizontally or vertically. When it comes time to clean the filter, the flip-top cover makes it simple to do so. It has 3-way flow control and a spray bar that can be attached to the filter to facilitate oxygenation.


  • Sleek design with an easy-to-grasp water control panel and a new media cartridge that traps more waste
  • The handy flip-top lid makes it simple to access the filter cartridge for servicing or replacement.
  • Designed for freshwater, saltwater, and reptile aquariums up to 40 gallons in size.


  • Italian made
  • Fully submersible
  • 3 stage filtration


  • Cartridge based

Sicce Shark

The shark features a magnetic rapid uncoupling system, as per Sicce (MCS System). This implies that the filter chambers are kept in place by magnets and may be easily removed for servicing. The filter draws water from the bottom and has an adjustable input diameter to prevent small fish from entering.

It also contains a flow regulator and a venturi function for adding oxygen to the water. It is meant to be flexible, so you can add whichever filter media you desire. Sicce offers a variety of materials that you may purchase or add your own.


  • Water Flow and Flow Ducting Device
  • Water Flow Regulation
  • Tool-Free Maintenance


  • Sicce brand
  • Fully submersible
  • 3 stage filtration


  • Large
  • Ugly looking in the tank

What Are Internal Aquarium Filters Used For? (Best Uses)

Source: Green Aqua

Internal filters can be quite useful in certain situations. While canister and power filters are superior, they are not suitable for all applications. Let’s look at several scenarios in which an internal filter makes perfect sense.

Nano Tanks

First things first, A 20-gallon aquarium or less is an excellent option for an internal aquarium filter. Internal filters, such as the OASE, can maintain a low profile in the tank and reduce congestion. They have sufficient capacity to handle tanks of this capacity and may be quieter than power filters.

Shrimp Tanks

Internal filters, such as the Aquaeon type described earlier, may make excellent filters for freshwater shrimp aquariums. They provide three stages of filtration while remaining gentle enough not to harm the little shrimp.

Betta Fish Tanks

An internal filter makes great sense with the long fragile fins of fancier species of Bettas. The OASE is ideal for them since it can be put up in a corner with a heater. Your betta may then roam freely in the aquarium without fear of its fins becoming entangled in the intake. Or going too close to the heater.

Breeder Tanks

Breeder tanks, similar to shrimp tanks, require a soft flow and a gentle filter. If properly constructed, an internal aquarium filter can meet the requirements. They provide better filtration than sponge filters because they can filter in three stages rather than two.

Turtle Tanks

Turtle tanks benefit greatly from submersible filtration. They may be placed anywhere underwater to provide the necessary filtering. They will be quieter than canisters and power filters since they will pump the water at or below the waterline rather than above.

Axolotl Tanks

Finally, for Axolotl aquariums, a submerged filter is ideal. Given the quantity of waste these salamanders produce, you should acquire a larger filter. However, utilizing an internal filter over others will result in a quieter system. They may be placed anywhere in the water. You may place them anyplace your Axolotl feels most at ease.


When properly engineered, internal filters may provide filtration for any form of tank. Hopefully, this review has alleviated some of your buyer’s concerns about determining which filter is ideal for you.

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