Top 7 Best Internal Aquarium Filter Options (For Any Tank)

best internal aquarium filter
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Last Updated: September 4, 2023 by Flora Gibbins

Maybe you’re new to fishkeeping, or maybe you can’t afford the pricier external tank filters. Either way, you know filters are crucial to any aquarium, so you decided to use an internal one for now. But with numerous options in today’s market, how can you choose the best internal aquarium filter?

To choose the best internal filter for your tank, consider your budget, tank size, fish type, and filter preferences. Overall, Fluval U4 is the best based on its features. However, what suits one may not suit another, so we’re also recommending six other filters that may fit your tank.

Best Internal Filters For Different Aquarium Types

1. Fluval U4 Underwater Filter – Best Overall

If you’re looking for a versatile and feature-packed internal filter, Fluval U4 is your best bet. It can support 12- to 65-gallon tanks with an output of 65 to 260 gallons per hour, and it can cater to freshwater, saltwater, and reptile pets.

You can also easily adjust its water flow to suit the type of fish you’re keeping since it offers three flow options.

This is perfect if you’re keeping fish that thrive in fast waters or fish that can only live in gentle waters.

Moreover, this product allows you to position your fish tank filter vertically or horizontally. Horizontal placement works best on shallow aquariums, while vertical filter placement creates custom flow patterns or currents.

Likewise, this filter can keep your aquarium’s water clean using its 3-stage filtration system, which features foam pads to deal with large particles, poly carbon pads to remove small debris, and Biomax filter nodes to balance your tank’s water.

Best of all, if you struggle with cleanup or maintenance, you’ll also love Fluval U4’s filter top.

Its top can flip open, so you can change cartridges without dismounting the filter.

With this, maintaining your internal filter should be a breeze.


  • Flip-top filter top
  • Adjustable water flow
  • Suits different fish


  • Slightly expensive


Fluval U4 is for you if you want to cater to different fish types in the future or love having the ability to customize your tank’s water flow. It’ll also suit you well if you don’t like maintenance work.


2. Tetra IQ Power Filter – Best Budget Pick

You can’t go wrong with Tetra IQ Filter if you’re under a budget. It works best on 10- to 40-gallon aquariums with its output of 80 to 170 gallons per hour, but you can’t adjust its water flow.


You’ll never need to prime when using this filter.

It’s essentially a plug-and-play basic internal tank filter offering a fantastic 3-stage filtration using a mesh Bio-Bag, activated carbon, and a Bio-Scrubber sponge.

It also comes with suction cups or clips to hold the filter in place.You’ll need to submerge this filter in your tank, and those clips or cups should keep it in place.

The downside is that you can only use this filter vertically, but it shouldn’t be a problem considering its price.

Moreover, it doesn’t have a lid on top, so you can easily clean or replace the cartridges. When using this filter, you can just dip your fingers to unclog its cartridges or switch it for a new one.

Lastly, note that Tetra’s filter works best on medium-sized fish. If you’re thinking of using this for small fish, you may want to cover the filter with fine mesh to ensure the fish don’t get stuck in the filter.


  • Budget-friendly
  • Comes in different sizes
  • Easy installation and maintenance


  • Unadjustable water flow


Tetra Power Filter might suit you if you’re looking for the best internal fish tank filter on a budget. It sacrifices a few features to ensure its affordability, but it excellently and efficiently filters aquariums.


3. Penn-Plax Cascade 600 – Best For Quiet Operations

Penn-Plax Cascade 600 is for you if you want the quietest and best submersible aquarium filter on the market. It supports both freshwater and saltwater fish in a 50-gallon tank at an output of 175 gallons per hour.

It also features an adjustable flow switch and directional flow nozzles.With this, you can increase or decrease water flow when needed. You can also customize the current and water patterns.

Additionally, it proudly utilizes a Veturi Aeration option.

This feature frees you from needing an air pump as it already provides your tank with oxygenated and filtered water. So, as long as you set it up right, you should be good to go.

Likewise, this filter uses two filter media chambers and comes with the media themselves, so you don’t need to buy them separately. It also has a spray bar to evenly distribute filtered water on your tank’s surface and a classic three-stage filtration system.

Best of all, you can place it horizontally or vertically. This allows you to customize your filter preferences more, and it even provides you with suction cups to ensure the filter stays wherever you decide to place it.


  • Customizable media chamber
  • Adjustable flow
  • Doesn’t need an air pump
  • Can be placed vertically or horizontally


  • Maintenance may be difficult


If you’re looking for a feature-packed yet quiet internal aquarium filter, Penn-Plax 600 suits you. You may need some time to learn how to install and maintain it, but it’s worth it.


4. Aqueon Quietflow Filter – Best For Small Fish

You might find it hard to find the best internal filter for small fish like shrimp and others. If so, we happen to have the answer for you: Aqueon Quietflow Filter. It’s a top-mounted comprehensive filter that works well on keeping 3- to 20-gallon aquariums clean.

We’re not really sure which of its features impresses us more: that it can handle even the notoriously-messy freshwater shrimps despite its size or that it auto-starts and doesn’t require priming.

You read that right. This filter can autostart.

So, contrary to other internal filters out there, which would require you to manually turn them on if a power outage occurs, you’ll never need to worry with this filter. This filter resumes by itself as soon as it receives electricity, so you can go on vacations or faraway trips without being too concerned about your fish.

As for how it cleans messy aquariums with ease, we have its 3-stage filtration system to thank. It features a filter cartridge that handles the chemical filtration part and a coarse sponge for the mechanical part. It also has a Bioholster plastic grid meant to house beneficial tank bacteria.


  • Auto-start feature
  • Easy installation
  • Best for small fish


  • Noisy


If you want the safest yet most efficient internal filter for your aquarium with small fish, Aqueon Quietflow suits you. It’s meant for small creatures, but it’s powerful and can even auto-start.


5 . Zilla Internal Filter – Best For Aquatic Reptiles and Amphibians

Besides small fish, finding the best internal filter for aquarium reptiles is a challenge, too. Terrariums need highly capable filters to ensure their cleanliness, and Zilla Internal Filter does a great job doing this. You can easily install it in 20- to 40-gallon tanks using its hanging clips or suction cups.

Besides being a perfect fit for aquatic reptiles like turtles or amphibians like axolotls, Zilla’s best attribute lies in its grates.

It features a safety grate to ensure your pet’s safety.

This way, you don’t have to worry about your turtle, axolotl, or any other pet injuring itself.

However, since this filter utilizes a waterfall flow to clean aquariums, some people may find it too loud. Then again, if you prioritize having a powerful motor to ensure that your pet’s tank remains clean, it’s a fair trade.


  • Powerful
  • Has a safety grate
  • Perfect for reptiles and amphibians


  • A little too loud


If you’re caring for amphibians or aquatic reptiles and don’t mind loud machines, Zilla Internal Filter suits you best. It features a filter powerful enough to keep up with your pet and a safety grate to prevent injuries or accidents.


6. MarineLand Magnum Canister Filter – Best For Large Aquariums

MarineLand Magnum Canister is the best submersible aquarium filter for large tanks. It can support tanks with up to 97 gallons of water and filter 290 gallons per hour. Essentially, it’s perfect for fish keepers with large aquariums and a tight budget for external filters.

Moreover, this filter doesn’t need priming, so using it should be a breeze.

It also features two chambers for carbon or customizable media.

You can use the first chamber for chemical and biological filtration and the second chamber as a polishing cartridge for small particles not filtered by the first chamber.

If you’re a fan of using media or personalizing your aquarium accessories, we’re confident you’ll effortlessly fall in love with this filter. You can also rest assured that it can efficiently clean your large aquarium: it features a potent low rate and three stages of filtration.

More importantly, if you’re in it for the long run, you’ll like this filter’s corrosion-resistant housing material. With it, you don’t have to worry about having a damaged filter or needing a replacement within just a few months.


  • Suits large aquariums
  • Strong flow rate
  • Customizable filter media


  • Not for small aquariums


If you own a large tank and value quality over anything else, MarineLand Magnum is your best choice. You can easily install and customize it, too, so you’ll have a pleasant experience with this filter.


7. Marina I25 Internal Filter – Best For Small Aquariums

Nano aquariums are gaining popularity, especially in cities where tank spaces are limited. So, if you’re a small aquarium owner looking for the best internal filter, Marina I25 Filter might just suit you.

It features an adjustable flow rate for optimal water movement.

You can easily personalize the water flow according to the fish you’re caring for, so you’ll never need to worry about subjecting your fish to the wrong flow rate.

Besides this, it also comes with free media, so you don’t need to buy them separately unless you want to customize your used media. It also has suction cup feet, which can allow you to place it anywhere you want.


  • Suits small aquariums
  • Operates quietly
  • Features a waterspout


  • Can’t be fully submerged


If you own a small aquarium and want a highly-efficient internal filter, Marina I25 suits you. Despite its small size, it offers you plenty of room for customization and excellent filtration powers.


Do You Need An Internal Aquarium Filter?

You’ll need an internal aquarium filter if you have a small to medium aquarium or simply want a filter that you can use for the moment. An internal fish tank filter will ensure your fish live in clean and optimal aquarium water to strive and stay healthy, so it’s crucial to most aquariums.

You can use internal aquarium filters in a nano tank, shrimp tank, turtle tank, axolotl tank, breeder tank, Betta aquarium, and so on. Essentially, you can use internal filters on any aquarium as long as they can handle the filtration of the tank’s water.

How To Set Up An Internal Aquarium Filter

Most internal fish tank filters on our list are easy to set up, so you shouldn’t have a problem with them. Generally, you’ll just need to decide where to place your filter and attach it using its suction cups or hanging clips.

However, there are also instances where you’ll need to attach the air tube to help circulate your tank’s oxygen. When this happens, you’ll just need to connect the tubes to the filter. You may also check your filter’s instruction manual if it requires some complicated setup.

Things To Consider When Buying Internal Fish Tank Filter

You can’t simply point and pick when shopping for an internal filter for your aquarium. So, here are some factors you need to consider when buying an internal filter:

Flow Rate

You’ll need a filter with an adjustable flow rate that can keep up with your fish’s waste.


Some people can’t tolerate loud filters, while some people don’t mind the noise.


It’s best to have a versatile filter in case you decide to care for different fish.


If you tend to move your filter a lot or prefer an occasional different placement, add adjustability to the things you need to consider.

Frequently Asked Questions

How do internal aquarium filters work?

Internal fish tank filters work by sucking water from the bottom of your aquarium and processing that water through different filter media. Once the water passes through those media, it is then sent back to the aquarium either through spraying or a waterfall feature.

What is the quietest internal aquarium filter?

For us, Penn-Plax Cascade 600 is the quietest internal fish tank filter. However, runner-ups to this title also include Tetra Power Filter and Fluval U4.

Where should an aquarium internal filter be placed?

If your tank contains plenty of gravel and other small things, you can place your internal filter near the bottom and back part of your aquarium. Meanwhile, if you possess a sand-based tank, it’s best to place your filter around the top part of the tank.

Can I over-filter?

You can’t over-filter your tank, but you can end up exposing your fish to too much or too little flow. This is why it’s best to consider flow rate and whether or not you can customize the water flow when buying an internal aquarium filter.

Final Thoughts

For us, Fluval U4 is the overall best internal aquarium filter. It packs plenty of features at a great price, and we can’t see any flaws in it besides its price. However, if you’re on a budget, Tetra Power Filter is the best since it can provide powerful filtration at a low cost.

Then again, remember that the best internal filter for you will depend on your tank’s size, fish type, filter feature preferences, and budget, so we hope our review helped you find what’s best for you!

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