Stephen is an owner of several aquarium supplies shops in New York. Like no one else, he knows how to pick the perfect fish tank or any aquarium accessory from pump to artificial decorative plants.
Last updated: August 05, 2022
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Internal aquarium filters are the best alternative to a canister or hang-on-back filters if you have a small fish tank. They save on space, are incredibly affordable, and offer effective filtration. If you have a large fish tank, you can still get an internal aquarium filter to back up your existing filtration system.
We have put together a list of the 7 best internal aquarium systems after having a closer look at a couple of them. The products are the best-rated on the market, and they have nearly all the features that make an excellent internal aquarium filter. Some of the features that influenced our selection include; durability, ease of use and installation, warranty, flow rate, and filtration system. These features are the primary determinants of the performance and longevity of the filters.
More features: saltwater compatible, horizontal and vertical mounting, adjustable water flow, 12 W power output
This is our top pick for all the right reasons. The Fluval U4 is an excellent low-maintenance filter with a whopping output of up to 260 gallons per hour. It is compatible with saltwater and is designed for optimal biological and chemical filtration. It features a 2-pack carbon filtration pad that removes excess toxins effectively to ensure the water has a good balance. Installing the filter is not a walk in the park, but anyone can do it. You can mount it horizontally or vertically.
The Fluval U4 stands out among its peers because of its quiet operation, and you will not hear anything when it is operating. It is a perfect choice for anyone with a 65-gallon fish tank with either fresh or saltwater. Its compact size makes it ideal for small tanks, but you can also make the most out of it if you have a medium-size tank that’s is against a wall and cannot accommodate an external tank.
What makes it stand out?
We liked the filter’s compact build and high efficiency. It offers both biological and chemical filtration, ensuring your aquarium’s water has an optimal balance. Also, you will love how easy it is to maintain the filter. All you have to do is replace the filter media occasionally and remove the large particles from the intake area.
Which disadvantages must you keep in mind?
Although the Fluval U4 ticks almost all the checkboxes for the ultimate internal aquarium filter, it has a few shortcomings. First off, installing it takes a bit of work, which is typical of internal aquarium filters. Also, it doesn't offer optimal mechanical filtration, and it cannot filter anything floating on top of the tank.
More features: adjustable direction water flow, 2.25 lbs weight, internal sponge
This is handsdown the best internal aquarium filter for 50-gallon aquariums, and it is suitable for both fresh and marine water use. The filter features a 3-stage filtration system and 2 media chambers; one for foam and another for activated carbon. The foam filters particles and houses beneficial bacteria, while the activated carbon cartridge filters the toxins, bad odor, tannins, and any other harmful chemicals.
The Cascade 600 distinguishes itself with an adjustable and directional outflow. Its spray bar allows you to increase the oxygen level in the tank. All you have to do is connect the air tube and air muffler to the flow nozzle. As if that’s enough, the filter runs quietly and is reasonably priced. This makes it a great option for anyone looking for a powerful internal filter with great value.
What makes it special?
We found the customizable media chamber pretty impressive. Also, installing the filter is not a hassle, and you can place it either vertically or horizontally depending on how deep or shallow your fish tank is. Moreover, the filter allows you to control the flow and oxygen levels in your fish tank.
What cons did we find?
The Penn-Plax Cascade 600 is one of the best internal aquarium filters out there, but it falls short in some areas. For starters, the filter is not easy to maintain. Opening it up for routine maintenance takes some work. Also, it is not the best filter for a turtle tank.
More features: 3 lbs weight, quick setup, water polishing
Marineland is a popular brand that has built a name for itself in the fishkeeping industry with its top-quality products. This canister-type internal filter is one of their gems. It has a 3-stage filtration system and incorporates a pleated micron filter cartridge that provides crystal clear water. The best news is that you can change the cartridge with diatom to enhance the filtration efficiency.
The best thing about the MarineLand Magnum ML90770-00 is its customizable media and its ability to filter up to 97 gallons of water. This makes it a prime choice for larger fish tanks with either fresh or saltwater. You can also use it in a turtle tank with high bioloads. Its efficiency is similar to that of a canister filter.
What are our favorite features?
We were super-impressed by the rechargeable micron cartridge. It’s a rare feature. Also, the customizable media chamber and the ability to filter so much water sets the filter apart. The filter is suitable for all types of aquariums and has proven high-cleaning efficiency. Installing it is a breeze thanks to its lightweight build and simple design.
What could be better?
We found the filter relatively noise. If noise is a deal-breaker for you, look elsewhere. Also, the filter's cartridges block too early and you may be required to clean or replace them every few weeks. Another thing, when something is pulled into the impeller, the noise becomes too much. If the noise is too much, you can always check for clogging or damage.
More features: suction feet, adjustable water flow nozzle, 1.7 lbs weight
OASE makes high-quality fishkeeping products with beastly functionality and this Bio plus Thermo filter is no exception. The internal aquarium filter has a 3-stage filter system with filter foam and activated carbon foam. You can switch out either of the foams with a 30ppi fine foam for enhanced filtering efficiency. The most exciting thing is that the filter will keep running even when you are switching the media.
The most outstanding thing about this filter is that it can house the OASE aquarium heater, keeping it out of sight and away from your aquarium’s inhabitants. This makes it an ideal choice for anyone looking for a heater and an internal filter. Plus, it is designed to skim the surface of the fish tank to prevent scum build-up and you can tune-up or down the tank’s flow with the adjustable dial.
What are our favorite features?
We fell in love with the filter’s professional and clean design at first sight. Its build is also robust and reliable, typical of German brands. We also liked the customizable filter chamber and the adjustable water flow nozzle that you can use to control the flow. What’s more, you get a 3-year warranty.
What could be better?
The professional design and top-level performance of the OASE Bio plus thermo filter comes at a cost. It has a pretty steep price point. We also discovered it is not easily accessible. The filter is rare and you may only be lucky to find it at a local fish store near you.
This is another compact and quiet in-tank filters. It lives up to its name with a super-quiet operation. The tetra whisper filter is available for 10, 20, 30, and 40-gallon tanks. Compared to others on this list, it is a pretty basic filter with a dual-sided mesh for cleaning the tank. One side of the bio-bag filter cartridge is meant to catch debris and the other is a bio-scrubber meant for biological filtration.
The Tetra whisper filter is the best affordable internal aquarium filter out there. It offers excellent value for money and is a perfect choice for anyone looking for a low-budget yet reliable option. Beginner fish keepers with small aquariums would make the most out of this unit. It is super-easy to install and maintenance is hassle-free.
What do we love it for?
We loved how easy it is to install and maintain the Tetra Whisper filter, thanks to its simple design. We also loved its ultra-quiet operation. It’s a great choice for anyone on a tight budget as it is incredibly cheap and it comes in 3 different sizes, suitable for all types of small aquariums.
What were we disappointed with?
The Tetra Whisper filter falls short in some areas. We were disappointed to discover that the position of the filter and the water flow is not flexible. Also, it takes up much space in the aquarium despite being designed for small aquariums. To top it all, the filter is not the most durable unit out there, but it will serve you well in the short term.
More features: 5.25 ft cord, 15 W power consumption, 1.5 lbs weight, 4 nozzle
This is one of the best feature-packed submersible internal aquarium filters for large fish tanks that money can buy. It has a 2-stage filtration system that creates a clean and fresh living environment for your aquarium’s inhabitants. It offers an impressive flow rate of 400gph and it comes with a water pump designed for reliability and ultra-quiet operation. You can adjust the flow rate as you desire and choose either of the 4 nozzles to clean your aquarium.
The most unique thing about the NO.17 aquarium filter is the filter nets on its fountain pump that filter large blocks during pumping to prevent clogging. This enhances the circulation system, ensuring the water in your fish tank is clean and fresh. The filter is a prime choice for anyone with a large fresh or saltwater fish tank. Besides an aquarium, you can also use it in ecological pools, breeding ponds, and rock garden fountains.
Why is it special?
we love the versatility of the filter and its reliable, high-quality build. Assembling, installing, and maintaining it is a breeze thanks to its compact design. If quiet operation is a big deal for you, then this filter is your best bet. It is developed with a high-quality motor that produces little to no noise.
What are the flaws?
although it is advertised to work for large tanks, you’ll be better off using this filter as backup because its design leans towards creating more water currents than actual filtration. Also, we noticed the filter offers a small surface area for the growth of beneficial bacteria and its attachments do not increase water flow rate drastically as advertised.
More features: clip and suction cup mounting, automatic start, 1.5 lbs weight
The Aqueon QuietFlow internal aquarium filter is a justifiable buy for 40-gallon fish tank owners. It has lots of unique features that set it apart from its market peers. The 3-sage filter cleans and filters water efficiently. It is easy to install with hanging clip and suction cups. Maintaining it is equally easy as you only have to change the filter cartridge every 4 weeks.
If you have a 40-gallon tank and you are looking for a top-quality internal filter, the Aqueon QuietFlow should be your top consideration. It offers biological, chemical and mechanical filtration. The carbon cartridge incorporated in its design offers chemical filtration. Mechanical filtration is offered by the coarse media sponge, and biological filtration by the bioholster which removes toxic ammonia and nitrites.
What are our favorite features?
For us, the most impressive feature of the Aquoen QuietFlow Internal aquarium filter is the auto-start pump that requires no priming and restarts automatically if power is interrupted. Another great thing is that the carbon cartridge can remove foul odors and discoloration from water. Also, very few in-filters have the mechanical filtering capability.
What could be better?
It’s so funny that this filter is called QuietFlow when it is annoyingly noisy. We couldn’t stand the horrible rattling noise its motor produced. If quiet is what you are looking for, steer clear from this filter. On the bright side, its performance is stellar. Anyone who doesn’t mind the noise can make the most out of it.
Things to Consider
Without proper information, you can get overwhelmed with all the internal aquarium filter options on the market. This section has all you need to know to make the best-informed choice.
Benefits of Underwater Aquarium Filters
Underwater or Internal Aquarium filters have got lots of pros, hence are a top choice for many fish keepers. Here are some of the benefits of internal aquarium filters;
Affordable- these filters are easily accessible at pet stores and are reasonably priced.
Easy to install and maintain- in-filters are a breeze to set up and operate. They use electricity and most brands are generally quiet.
Great for beginners- Since they are affordable, readily available and easy to operate, in-filters are a prime choice for fish-keeping novices. Beginners are likely to start with small to medium-sized aquariums which in-filters are best suited for.
How to Install Submersible Aquarium Filter
As mentioned before, internal filters are very easy to set up. First, you need to get a spot for it on your aquarium. According to experts, the back corner of your fish tank is the best place to install an in-filter. Most models come with suction cups and hanging clips for attaching to the desired spot in the aquarium.
Internal filters come with an air tube which has to be attached at the point above where the water comes out. The tube is meant to bring clean air into the tank when clean water is poured back into the aquarium. The air mixes in the water to oxygenate it. If you have plants in your aquarium, avoid using the air tube as it will take out all the carbon dioxide needed for their growth.
When installing an in-filter, ensure it is completely immersed in water. Any parts hanging out can heat up and burn the coil. If you are using the air tube, ensure its end sticks out of the tank.
How to Pick the Best Internal Aquarium Filter
Here are some of the aspects you must consider when choosing an internal aquarium filter to make the best buy;
Filtration system and stages
Internal aquarium filters have different filtration systems. Most models come with either 3-stage or 2-stage filtration systems. For optimal filtration, go for a model with a system that offers biological, chemical and mechanical filtration like the Aqueon QuietFlow E. Besides removing particulates, it will ensure your fish tank’s water is free of bad odors and toxins.
Internal aquarium filters have various water flow rates, you need to choose it by tank size and quantity of decor
Industry experts recommend
Trusted SourceAquarium FiltrationAquarium filtration makes all the difference between healthy fish and poorly-kept fish
Trusted SourceInvasive Mycobacterium marinum Infections
Mycobacterium marinum infections, commonly known as fish tank granuloma, produce nodular or ulcerating skin lesions on the extremities of healthy hosts. Delay of diagnosis is common, and invasion into deeper structures such as synovia, bursae, and bone occurs in approximately one third of reported case-patients
. Here’s what you need to know to keep your tank in shape![/trusted_link]filters with slow flow rates for aquariums with plants and small fish. If your aquarium has larger fish, then you can go for filters with higher flow rates like the NO.17 Submersible Aquarium Internal Filter.
This is a crucial consideration if you want optimal performance from your filter. You have to get the right filter with a capability of cleaning the water in your aquarium. For instance, if you have a 50 gallon aquarium, go for a model with a cleaning capacity of 50+ for optimum performance.
This matters so you know how much aquarium space you’ll be setting aside for the filter. If you have a smaller aquarium go for a filter with a compact design so that it doesn’t take up much space. Also, smaller and lightweight filters are much easier to install and handle during maintenance.
Durability and warranty
Durability is key, unless you don’t mind going back to the store for a new filter every now and then. Choose a model built with rugged materials that can be used in both fresh and saltwater aquariums. The warranty says much about the brand’s quality. A longer warranty period shows that the manufacturer trusts their build quality. Some brands offer up to 3 years warranty while some like the NO.17 Submersible Aquarium Internal Filter offer 180 days limited cover.
Internal aquarium filters come with suction cups/feet and/or hanging clips for installing them to the aquarium.
Some models allow you to mount both horizontally and vertically according to the depth of your aquarium.
Ease of use and installation
If it’s not easy to install and use, you will hardly use. Choose models that come with straightforward installation instructions. Luckily, internal aquarium filters are generally easy to install. Some models like the Penn-Plax Cascade 600 are easy to install but need some work when it comes to maintenance.
Start by removing the filter from the water. Get a net for catching the debris that falls off the filter when you are lifting it up.
Place the filter in a bucket full of water then swish it around to loosen the debris on it. Start disassembling the filter and ensure all the parts remain submerged. Scrub the gunk off the filter’s sponge with an aquarium brush or an old toothbrush. If the filter’s impeller or tubing is clogged, dislodge it with a thin aquarium brush or earbud then clean between the blades. Rinse all the filter’s parts in clean water then assemble and re-install it.
You should change your filer’s media once every month or every time you clean the filter. The chemical medium has to be changed once every month because once it is filled up, it cannot absorb more toxins.
A high-quality filter is essential to maintaining good water quality conducive for your aquatic pets and plants. Our roundup has the best internal aquarium filters on the market. The list has something for everyone, from the small fish tank owner on a tight budget to the fish keeper ready to splurge for the best quality available.
Our top pick, the Fluval U4 is the best that money can buy. It is reasonably priced, yet it has all the features you would need from an in-filter. It has an efficient 3-stage filtration system and is super-easy to install. Our second option, the Penn-Plax Cascade 600 is the best you can get for your 50-gallon aquarium.
Our third choice, the Tetra Whisper Internal Filter For Aquariums is the best canister internal filter you can get at its price point. It packs a punch with a ton of incredible features like a rechargeable micron cartridge and a customizable filter media chamber.
Aquarium filtration makes all the difference between healthy fish and poorly-kept fish