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Fish Tank Filters

At Aquacadabra, we have one of the largest selections of aquarium filters and filtration equipment in the UK. From airpumps and external canister filters, to protein skimmers and UV sterilisers - our range caters for all types of fish keepers. We have products suitable for Coldwater, Tropical, Marine and Invert keepers (we also have pond filters in our Pond section) If you're new to fish keeping, you may find our article 'The Basics of Filtration' on our Blog useful as a little background reading. We’ve also provided a quick over view of each approach to filtration at the bottom of this page. To navigate through our Filtration category, simply click on the appropriate category on the left, or on the links below. Should you need any advice, please feel free to contact us, we would be happy to help you with your selection.

View our Fish Tank Filters Categories

Air Pumps
External Fish Tank Filters
Filter Media
Filtration Systems
Fluidised Filters
Internal Fish Tank Filters
Protein Skimmers
Pumps & Powerheads
UV Sterilisers

External Filters:

If you’re keeping coldwater or tropical fish, external canister (or power) filters are highly recommended as the best approach to filter your fish tank, especially if the tank is more than 150lts. External filters have a large canister which allows you to provide media specific to your requirements. You can also add plenty of media - the more the better as this provides the space on which your beneficial bacterial will grow. Another great advantage of an external filter is that they can be placed below or at the side of your aquarium, reducing the amount of equipment you need to hide within your fish tank and making it easier to maintain the filter.

External filters can be used on fish only marine aquariums, however they can cause issues if you’re looking to keep sensitive reef inverts, as their efficiency in breaking down nitrites into nitrates can lead to problems!

Internal Filter:

Nowadays internal power filters are seen as the minimum requirement if you’re wanting to successfully keep fish in a fish tank – and if you’re a newcomer to the hobby they’re a great place to start. They’re often more competitively priced when compared to an external filter and they’re easier to install. Generally fitted with suckers, the internal filter is attached to the back glass inside your tank. A water pump in the top of the filter draws aquarium water through a filter foam or cartridge, which strains out larger debris and which provides a surface for beneficial bacteria on which to grow. The cleaned water is pumped out at the surface of the fish tank, helping to oxygenate the aquarium.

Internal filters are ideal for fish tanks up to 200lts and are really easy to use, making them perfect for the beginner.

Pumps and Powerheads:

Historically powerheads were designed for use on undergravel filters. A filter plate would be placed below the gravel of your fish tank and the powerhead would draw water through the gravel, by an uplift tube and then return it to the fish tank’s surface. Using the aquarium’s gravel as a filter bed is no longer in fashion. Instead, powerheads and pumps now tend to be used specifically for water circulation, either in the tank if you’re keeping marine fish and inverts, or to provide water flow to auxiliary equipment such as UV Sterilisers, Chillers or Sumps.

Our range of Pumps and Powerheads is vast, with products available that can pump anything from 30lph to 20,000lph – so make sure you select the appropriately sized pump!

Filter Media:

We stock a huge range of filter medias, some of which are designed specifically for a particular filter such as cut carbon pads, whilst others are more general and can be used in a variety of applications. Filter medias are used to provide a mechanical, biological and chemical filtration, helping you to maintain a healthy environment for your aquatic live stock. For more information about the filtration process, our Blog Article goes into more detail.

We stock filter medias from the likes of API, Aqua Medic, Eheim, Fluval, Juwel, Rowa, Seachem and Tetra; with great discounts provided where ever possible.

Air Pumps:

Traditionally airpumps were used to draw water through an undergravel filter plate, as a rudimentary approach to filtration (which is still used by Reef One). This approach is now unfashionable as internal filters have become more readily available, providing superior approaches to filtration.

Air Pumps are however still used by many, where they can provide additional oxygenation when used in conjunction with an airstone, or to provide air to a decorative feature. If you’re using Reverse Osmosis water, or mixing marine or reef salt, an airpump and airstone is a cost effective piece of equipment for this purpose (and I personally recommend this – mix you’re salt water in a water butt and just leave it bubbling away until you need it!).

UV Sterilisers:

If you’re keeping sensitive and disease prone fish, particularly when treatment with medications is difficult e.g. you have marine inverts which prevent the use of copper based medications, a UV Steriliser is a great way of reducing the likelihood of a disease outbreak.

Water is pumped through the UV Steriliser (a pump is required), where it passes a UV bulb which sterilises the water – the UV radiation kills bacteria and parasites. UV Sterilisers are highly recommended as they’re very efficient; they’re even used by the water utilities supplying drinking water!

We stock a number of models of UV Steriliser, together with replacement UV bulbs.

Protein Skimmers:

These filters are designed for use in marine and invert aquariums (not freshwater), and they’re highly recommended – anyone keeping marine fish should have a protein skimmer – they’re extremely efficient and when used in conjunction with live rock help to create and maintain ideal water conditions for these sensitive marine creatures.

Water is passed through a cylinder into which huge volumes of air are injected, usually by a venturi or on older style protein skimmer by an airpump. As the water passes through the tiny bubbles created, impurities in effect stick to them, rising to the top of the cylinder. This can then be easily removed by empting a collection cup.

Filtration System:

This group of products are complete filtration systems which are generally designed to provide a sump based system for a marine and invert aquarium. They’re placed in the cabinet below the fish tanks where they are plumbed in to the aquarium. They tend to include (or have space for) items such as protein skimmers, calcium and nitrate reactors and return sump pumps.

If you’re after an off the shelf, well made and fully functioning filtration system for your reef aquarium, these systems are ideal (if a little expensive!).


This type of filter tends to be used for specialist applications, where they are used to target a particular pollutant such as Nitrate. Water is passed very slowly through the reactor, where one variety of bacteria consumes all of the oxygen, creating anaerobic conditions. A second type of bacteria that requires these conditions then consume the nitrates.

Phosphate reactors are also available, which use chemical filter medias to remove phosphates and silicates from the water that is past through them.

Fluidised Filters:

These are chambers within which a filter media is placed. Water is pumped through the chamber, in an upward direction before being returned to the aquarium. This water movement agitates the media and places it in a fluidised state. As rapid water movement is required, these filters are great places to establish huge beneficial bacteria colonies, or to maximise the efficiency of activated carbon of phosphate removing resins.


In effect Ozone works as a disinfectant, killing any bacteria which come into contact with the gas, which again is a process regularly used by water utilities. An electrical charge is used to break the atomic charge of oxygen atoms, creating ozone. The gas produced is then pumped into the aquarium’s water (usually into a protein skimmer) where any bacteria that come into contact with the ozone perish.

Again this is quite a specialist application, so feel free to contact us if you’d like any advice.