Your aquarium is your fish’s entire world, so you need to create a healthy environment for them. Aquarium and fish tank filters help clean and purify tank water, removing fish waste, old food, decaying organic matter, and potentially harmful chemicals, such as ammonia. As such, an aquarium filter is a must-have for any fish tank, even a small one. It’s one important factor in providing a suitable home for your fish or other aquatic critters. Of course, you still need to heat and clean your fish tank, but you shouldn’t overlook filtration.
We reviewed dozens of aquarium filters to identify the best of the best. To reach our conclusions, we examined a range of factors including filtration type, flow rate, media, noise levels, and average customer reviews.
After considering a huge number of choices, it was clear the Fluval FX4High Performance Aquarium Canister Filter should be our top pick. It turns over 700 gallons of water an hour and holds a whopping gallon of media; mechanical, chemical, and biological.
The 5 Top-Rated Aquarium & Fish Tank Filters
|Best Overall||Fluval FX4High Performance Aquarium Canister Filter||4.2|
|Runner Up||Marineland Penguin PRO Power Filter||4.3|
|Best Budget Buy||Marina Power Filter||4.2|
|Best Under-Gravel Aquarium Filter||Lee’s 40/55 Premium Undergravel Filter||4.3|
|Best Canister Aquarium Filter||Fluval FX4High Performance Aquarium Canister Filter||4.1|
*Ratings are from Amazon at the time of publication and can change
Our Top Pick: Fluval FX4High Performance Aquarium Canister Filter
Need a powerful filter for a large aquarium? The Fluval FX4High Performance Aquarium Canister Filter should be high up on your list! It has an effective five-stage filtration system, providing all three types of filtration: mechanical (removing particles from the water), biological (utilizing colonies of nitrifying bacteria that turn ammonia into nitrites), and chemical (using media that removes chemical impurities from water).
This filter can pump 700 gallons of water through its system each hour and is suitable for tanks of up to 250 gallons. Like all canister filters, it sits outside the tank, making it easy to maintain the unit and change the filter media. The convenient outlet pipe and smart pump make it extremely easy to carry out water changes, siphoning water off via the filter, rather than manually bailing it out.
The large, stackable media baskets can hold as much as a gallon of filtration media. All media is included, but you can choose to use your own, if you prefer. This is an excellent filter overall, but at $280, it doesn’t come cheap.
Fluval FX4High Performance Aquarium Canister Filter Key Features:
- Microchip in the Smart Pump monitors and improves performance
- Self-starting mechanism
- Compact design to fit under aquarium
Our Runner Up Pick: Marineland Penguin PRO Power Filter
Not everyone needs an aquarium filter as powerful as our top pick, or has the budget for it. The Marineland Penguin PRO Power Filter is a much more affordable choice. It comes in a range of sizes including: up to 20 gallons ($25.17); up to 30 gallons ($35.25); up to 50 gallons ($36.04); up to 75 gallons ($57.25); and up to 90 gallons ($75.98).
The quality might not quite live up to the standards of our number one choice, but it provides simple and effective mechanical, chemical, and biological filtration. It’s also designed to be ultra-quiet, which is no doubt a very handy feature. This filter comes with a “Bio-Wheel” that provides biological filtration by efficiently eliminating toxic ammonia and nitrate.
Marineland Penguin PRO Power Filter Key Features:
- Provides mechanical, chemical, and biological filtration
- Bio-Wheel helps keep tank free from ammonia
- Replacement filter cartridges are widely available
Best Budget Pick: Marina Power Filter
If you’re searching for a simple option for a compact fish tank, the Marina Power Filter is an excellent choice. It comes in three sizes, for up to 10, 15, and 20 gallons, ranging in price between $11 and $22. Four filter cartridges are included: two Bio-Carb and two Bio-Clear, however, it is possible to customize this filter by adding your own choice of media.
The slimline design makes the Marina Power Filter easy to fit even in small spaces where you don’t have much room around your tank. The downside is that it doesn’t provide as much space for media as bulkier alternatives. The flow rate of this filter is adjustable, which is great for fish who don’t like too much movement in their water.
Marina Power Filter Key Features:
- A great choice for small aquariums, such as betta tanks
- No priming required
- Quiet operation
Best Under-Gravel Aquarium Filter: Lee’s 40/55 Premium Undergravel Filter
Under-gravel filters aren’t the most common aquarium filters, but their simple operation makes them a great choice for fish-keepers who prefer minimal upkeep. Lee’s 40/55 Premium Undergravel Filter is our favorite under-gravel option on the market right now. As the name suggests, it sits under the gravel at the bottom of your tank, where it can build a colony of bacteria that goes largely undisturbed. There’s no need to change media or service moving parts, but it is much easier to install in a bare tank than add to an existing aquarium setup.
This model measures 12 inches by 48 inches, so it’s designed for use in fairly large tanks. The under-gravel plates are made from extremely durable material, which resists cracking and should last for years to come. Retailing at $72, this isn’t the cheapest choice around, though it’s important to keep in mind you’ll get what you pay for. Another thing to be mindful of is that if your fish produce a large amount of waste, you may find you need to use it in conjunction with another type of filter, such as a power filter or canister filter.
Lee’s 40/55 Premium Undergravel Filter Key Features:
- Suitable for marine and freshwater use
- Filters water naturally
- Comes with free carbon filter
Best Canister Aquarium Filter: Polar Aurora 4-Stage External Canister Filter
Looking for a powerful canister filter without an astronomical price tag. At $79, the Polar Aurora 4-Stage External Canister Filter isn’t exactly inexpensive, but it’s reasonably priced compared to other filters with its capacity, and it arguably does just as good a job. That’s why it’s our favorite canister filter (after our overall top pick). It comes with four internal trays, to which you can add your own choice of mechanical, chemical, and biological filter media. Plus, it has a 9-watt UV sterilizer that helps kill algae spores and bad bacteria for cleaner, healthier water.
It’s overall flow rate is 525 gallons per hour and it’s suited to tanks of up to 200 gallons. The self-priming pump makes this filter extremely easy to set up and use, with no manual siphoning necessary to get it going.
Polar Aurora 4-Stage External Canister Filter Key Features:
- Super quiet operation
- Easy to customize the media you use
- Two spray bars included
Who Should Buy a Fish Tank or Aquarium Filter
Anyone who keeps fish (or other aquatic critters, such as shrimp or water snails) should buy an aquarium filter. It’s imperative that you use some kind of filter in your fish tank to keep the water clean. Otherwise fish waste and other dirt and debris will build up, ammonia levels will rise, and your fish will get sick and likely die.
An aquarium filter isn’t an optional extra in your fish-keeping arsenal, it’s an essential.
Important Features to Consider
An aquarium filter should have a few important features. Here’s what to consider when selecting a filter for your aquarium:
- Filter type. You’ll find a range of filter types available. Power filters are perhaps the most common option as they’re fairly inexpensive and generally let you customize the media you use, but they can be loud and require a fair amount of maintenance. Canister filters are an effective choice for large aquariums providing superior filtration to any other type of filter, but they are large and expensive. Sponge filters are cheap and easy to use, providing mechanical and biological filtration. However, they can look bulky in the tank and you need to use them with an air pump. Under-gravel filters are great at building a colony of beneficial bacteria but you may find you need additional mechanical and chemical filtration, especially in a large tank.
- Media. Filtration media are the various substances used to filter water in your tank. Many types of filter come with media cartridges included, which may provide mechanical, biological, or chemical filtration, or a combination of the three. However, the majority of aquarium filters also let you add your own media.
- Flow rate. The flow rate is measured in gallons per hour and is the amount of water that the unit can filter in an hour. It’s important that you choose an aquarium filter with an appropriate flow rate for the size of your tank. More on that later.
- Noise levels. Unfortunately, some aquarium filters can be quite noisy. This isn’t a problem if your fish live in a room that you don’t frequent too often, but it can become irritating if your fish tank is in your bedroom or main living room. That said, some modern filters are designed to be extremely quiet, if not silent. Look for models that advertise their low volume as a selling point.
Frequently Asked Questions
What is an aquarium filter and how does it work?
As the name suggests, an aquarium filter is a device that removes dirt and potentially-harmful chemicals from the water in your fish tank, as well as oxygenating it so your fish can “breathe.” Different types of aquarium filters work slightly differently, but they generally feature a tube that sucks dirty water in from the aquarium and pushes it through the media inside. The media traps dirt and removes impurities from the water, leaving it clean and fresh. This clean water is then returned to the aquarium via another tube or a waterfall-style system.
What size aquarium filter do I need?
It’s important you choose the right size of filter for your aquarium. The larger your aquarium the larger the flow rate you’ll need from your filter. Most aquarium filters list what size aquarium they’re suitable for, but generally the hourly flow rate should be three to four times the total volume of your aquarium. So, if you have a 40-gallon tank, your filter needs a flow rate of between 120 and 160 gallons.
Do I need an air pump if I have a filter?
Most aquarium filters oxygenate the water, so there’s no need to have an air pump, too. The exception is sponge filters that require an air pump to work.
Can a fish survive without a filter?
In theory, hardy fish can survive without a filter, but they won’t have a good quality of life and their lifespan is likely to be shortened. Fish more sensitive to water conditions might not survive at all. Plus, it will mean a huge amount of extra work for you, since you’ll need to perform water changes every few days just to keep the tank relatively clean.