A well-chosen aquarium filter is the unsung hero of a thriving fish tank, keeping the water clean, oxygenated and free from harmful toxins.
Whether you’re a beginner setting up a small home aquarium or an experienced aquarist maintaining a large, heavily stocked tank, the right filter can make all the difference to your fish’s health and the overall clarity of your water.
The best aquarium filters go beyond simply moving water around - they provide essential mechanical, biological and chemical filtration to remove waste, break down harmful ammonia and nitrates and keep odours at bay. All of the essentials you need for a thriving aquarium on a long-term basis.
What should you look for in an aquarium filter?
When selecting a filter, first consider the size of your aquarium. Filters are rated based on the volume of water they can handle, so you’ll need one with the appropriate flow rate for your tank. A good rule of thumb is to choose a filter that can process at least four times the volume of your tank per hour.
Next, think about the type of filtration you need. External canister filters offer powerful, multi-stage filtration for larger tanks, while internal filters and hang-on-back options are great for smaller aquariums. If you prefer a low-maintenance option, look for models with easy-access filter media compartments and self-priming features.
Noise levels, energy efficiency and ease of cleaning are also key factors to keep in mind. A quiet filter is essential if your aquarium is in a bedroom or living space, while an energy-efficient model will save you money in the long run.
We’ve rounded up the best aquarium filters to suit every tank size, budget and level of expertise.
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Fluval FX6 Canister Filter
This Fluval FX6 is a powerhouse when it comes to aquarium filtration. Designed for tanks up to 1500 litres, this high-capacity canister filter delivers impressive water clarity with multi-stage filtration that removes debris, chemical impurities and harmful toxins.
Its smart pump technology automatically purges trapped air, ensuring optimal performance without constant maintenance. Its stackable media baskets allow for full customisation of filter media, giving you control over water quality. If you’re after serious filtration power for a large aquarium, the FX6 is a top-tier investment.
Buy now £305.99, Amazon
Seachem Tidal Hang-On Filters
If you need an efficient, low-maintenance filter without taking up valuable tank space, this Seachem Tidal Hang-On Filter is a fantastic choice. Designed for aquariums up to 130 litres, it features an adjustable intake flow, self-priming pump and built-in surface skimmer to remove floating debris.
Its unique maintenance alert lets you know when the filter media needs cleaning, making upkeep effortless. Ideal for beginners and seasoned aquarists alike, the Tidal filter ensures crystal-clear water with minimal hassle, all while being whisper-quiet in operation.
Buy now £48.99, Amazon
Fluval FX4 Canister Filter
A more compact sibling to the FX6, the Fluval FX4 delivers the same exceptional filtration performance but is better suited for aquariums up to 1000 litres. With a powerful yet energy-efficient motor, it cycles an impressive 2,650 litres per hour, keeping your tank clean with minimal effort.
Like the FX6, it features self-priming technology, air auto-purging and stackable media baskets for custom filtration setups. Whether you’re running a freshwater or marine tank, the FX4 is a reliable workhorse that offers premium quality in a more manageable size.
Buy now £247.99, Amazon
Eheim Classic Vario+e 250 External Filter
The external filter of the Eheim Classic Vario+e 250 is known for its durability, efficiency and near-silent operation. Designed for aquariums up to 250 litres, it offers electronic flow control, allowing you to adjust water turnover rates to suit different tank setups.
The high-quality ceramic components ensure longevity, while the large filter volume supports optimal biological filtration.
Buy now £196.99, Horizon Aquatics
Oase BioMaster 850 External Filter
The Oase BioMaster 850 is the ultimate filtration system for demanding aquarists. With a built-in pre-filter module, it traps debris before it even reaches the main filter, reducing maintenance and extending the filter media lifespan. Its Thermo model also includes an integrated heater, keeping your tank temperature stable while saving space inside the aquarium.
Designed for tanks up to 850 litres, this external filter combines mechanical, biological and chemical filtration for outstanding water clarity. If you’re after a premium, all-in-one solution with cutting-edge features, the BioMaster 850 is a top choice.
Buy now £567.00, Amazon
Fluval U3 Internal Filter
A compact yet powerful choice, the Fluval U3 Internal Filter is perfect for medium-sized aquariums up to 150 litres. Its three-stage filtration system - mechanical, chemical and biological - ensures crystal-clear water, while the adjustable flow settings allow for customised circulation.
The clever flip-top design makes filter media changes quick and hassle-free, reducing maintenance time. Whether mounted horizontally for shallow tanks or vertically for deep ones, the U3 is versatile, quiet and efficient, making it an excellent pick for both freshwater and marine aquariums.
Buy now £30.00, Pets at Home
Oase BioPlus Thermo Aquarium Filtration + Heater
For aquarists who love a sleek, all-in-one solution, the Oase BioPlus Thermo is a game-changer. This internal filter not only delivers high-performance mechanical and biological filtration but also includes an integrated heater to keep your tank at the perfect temperature - without cluttering up your aquarium.
Designed for tanks up to 200 litres, it features an innovative modular design, making it easy to clean without disturbing your aquatic setup. Silent operation, energy efficiency and a discreet in-tank presence make this a premium choice for those who want superior water quality and a streamlined aesthetic.
Buy now £31.26, Swell
Interpet CF Mini Cartridge Filter
Small but mighty, the Interpet CF Mini is a brilliant internal filter for nano aquariums and small fish tanks up to 40 litres. Its simple yet effective cartridge system provides reliable mechanical and biological filtration, keeping water fresh and free from harmful toxins.
The compact design makes it easy to fit into smaller tanks without taking up valuable swimming space. Ideal for beginners or those maintaining a shrimp or betta tank, this affordable filter is low-maintenance, easy to install, and runs quietly - perfect for a fuss-free aquatic setup.
Buy now £21.50, Amazon
SuperFish Aqua-Flow 400
If you're after a budget-friendly filter that doesn’t skimp on performance, the SuperFish Aqua-Flow 400 is a solid option for tanks up to 100 litres. Its dual-action filtration combines mechanical and biological cleaning, effectively removing waste and supporting beneficial bacteria growth.
The Easy-Click filter cartridge system makes media changes quick and straightforward, reducing maintenance time. It’s compact, energy-efficient and operates quietly - ideal for both freshwater and tropical tanks.
Buy now £14.26, Amazon
Eheim Pick Up 45 Internal Filter
Eheim’s reputation for high-quality filtration is well-earned - and the Pick Up 45 is no exception. Designed for small aquariums up to 45 litres, this internal filter is perfect for nano tanks, bettas, and shrimp setups. Its unique "pick-up" system allows you to remove the filter unit without dismantling the entire setup, making cleaning incredibly easy.
With efficient mechanical and biological filtration, quiet operation and durable German engineering, this is a reliable, long-lasting option for maintaining pristine water conditions in compact tanks.
Buy now £22.99, Amazon
Verdict
The Fluval FX6 is the gold standard for high-performance filtration. Its massive capacity, smart self-priming system and customisable filtration options make it the best investment for serious aquarists. If you want unmatched reliability, efficiency and water quality, this powerhouse filter is worth every penny.
