When setting up a new fish tank, one of the most essential pieces of aquarium equipment to purchase is a filter. An aquarium filter is central to the health and wellbeing of your fish; ensuring that your water is clean, healthy and free from disease.

Whether you are new to fish keeping and you have a small fish tank, or you are an experienced hobbyist with a much larger aquarium, your filter is arguably the most important piece of equipment in your tank. By helping to oxygenate your water, and removing excess food, waste and harmful chemicals, an aquarium filter will help your fish and aquatic plants to thrive.

But as with any piece of equipment, the quality of the results that you get from your filter is only going to be as good as the set up and maintenance that you put into it.

So what can you do to get the optimum performance from your fish tank filter? We have outlined below some of the key aspects to consider with the purchase, set up and ongoing maintenance of your aquarium filtration system.

Purchasing the Correct Filter for your Fish Tank

When selecting the best aquarium filter for your tank, there are a number of things you will need to consider, such as the type and size of your fish tank, your livestock, budget and the amount of maintenance you wish to do. You can read more about choosing the best filter to suit your tank in one of our previous blog posts.

Installing your Aquarium Filter

After you have added your water, dechlorinator, and any additional decoration to your tank, it is time to add your filter to your aquarium.

If your filter comes with hosing, make sure to cut your hose to the required length. By removing slack in the hosing, you are creating a more direct path for your water, which will improve flow rate and stop debris from forming.

As a safety measure in the event that water was to run down your filter’s electrical cable, you will want to make sure that the cable has plenty of slack. To prevent the risk of an electrical short circuit, creating a safety ‘drip loop’ would direct any water down the cable and onto the floor, rather than entering your electrical socket.

After connecting your filter, it is important not to add any livestock to your tank until the water has been cycled. This process can take up to 2-3 weeks, and it ensures that the ammonia, nitrite and nitrate levels in your aquarium are safe for the addition of your fish. To start the cycle in your tank, put a small pinch of food in every few days for two weeks, then let it settle. We would recommend that you ensure that your tank is ready by using a testing kit.

NOTE - For customers replacing an existing aquarium filter – when replacing or upgrading to a new filter, do NOT simply remove the old filter and replace with your new model. By removing your old filter media you would also be taking out the denitrifying bacteria that have established, causing your ammonia levels to spike and potential harm to your fish.

Instead, take out some of the filter media from your existing filter and combine it with the media in your new filter, allowing the denitrifying bacteria to populate. Run both filters in your tank for a minimum of seven days, after which time you can remove your old filter.

Ongoing Maintenance of your Aquarium Filter

Once you have chosen the best filter for your aquarium, and you have set it up correctly in your tank, regular maintenance of your equipment and following the best practice guidelines below will help provide optimal performance of your filtration system:

Important: Disconnect mains electricity supply before handling or attempting maintenance. Always fully read and check the troubleshooting section within your product instruction manual. 

  • It is advisable to regularly monitor your filter’s flow rate – if it starts to slow down, this is often a sign that your filter needs cleaning.

  • Internal filters generally require cleaning every few weeks, whilst with external filters this can vary from between two weeks (for highly populated tanks) to every two months (for aquariums producing low levels of waste).

  • Avoid cleaning your filter when making changes to your aquarium, for example introducing new livestock, carrying out large water changes or altering your feed, as for these periods of time a stable tank environment is critical.

  • A clogged impeller is often the primary cause of all filter faults, so it is advisable to clean your filter’s impeller every month, to help improve the performance and overall lifespan of your aquarium filter. Gently wiping the impeller with a cloth will help to remove any algae or debris which has built up, and clean the shaft and housing with the tip of a cotton wool bud.

  • In the event that a breakage was to occur, it is always advisable to keep a supply of spare parts for your aquarium filter. Within just 2 to 3 hours of a filter becoming inactive, your filter bacteria will begin dying off, so planning ahead and having a spare impeller and other filter parts on hand will avoid any serious implications to your tank or livestock.
  • Ensure to lubricate all o-rings after each maintenance to ensure all seals are water tight. O-rings are perishable items and if worn down and not replaced can cause water ingress. Ensure to thoroughly check your o-rings as these parts are not covered under the manufacturing warranty. 
  • If you have a marine tank, you will also want to remove any calcareous deposits from the impeller.

  • Biological media will need to be replaced after approximately 12-18 months and sponges will need to be replaced every 6 - 12 months; however, it is important to NOT replace all of the media at once. By substituting a third of the media at a time, you will allow time for your denitrifying bacteria to colonise, maintaining the biological balance in your aquarium.

  • It is essential that you start checking your UV bulbs after about 6 – 8 months of use. After that, the bulb will not work to its full potential, and you will notice the ramifications in your tank

  • Activated carbon or zeolite will need replacing more often (usually every few months), and if you are using these, we would advise that you follow the manufacturer’s instructions.

  • Always clean your filter media with water from your aquarium, NOT mains water. To clean solid biological media, gently move them through the water to remove large particles of debris, and lightly squeeze your sponges in a container of water until the expelled water is reasonably clear.
  • It is important to have a container that is solely used for cleaning your filter media – any residue from cleaning products or chemicals could contaminate the water in your aquarium and cause harm to your fish.

  • Also check that any spray bars on your filter are free from debris, to help maximise water flow.

  • To enhance water flow through your filter and improve your filter’s performance, make sure to include plenty of pre-filter media to help avoid a blockage.

  • Unplugging or switching off your filter for a few moments whilst your fish are fed will help prevent food from entering your filter, reducing the build-up of debris.

  • To help stop air disturbance into your filter, make sure all hosing and locking connections are secured tightly.

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It is important to understand that every filter and tank environment is different, so whilst some aquarium filters may require weekly maintenance, others can be left for a month or two without any issues. This is something that you will get to learn through an element of trial and error, and by making a recording of the results, you will begin to determine the optimal cleaning cycle for your filter.