Aquarium Filters & Pumps for Beginners

In depth

Choosing your first aquarium filter and pump is a crucial step in setting up a healthy environment for your fish. It’s easy to get overwhelmed by the sheer number of options available, particularly because the terminology used can seem quite complex. Don't worry – this guide breaks down the key aspects you need to consider, focusing on what truly matters when starting out with a small aquarium. The primary function of any filter and pump combination is to maintain water quality; it does this by removing waste products produced by your fish and beneficial bacteria will then convert these into less harmful substances.

At its core, an aquarium filter works through a process called mechanical filtration, chemical filtration and biological filtration. Mechanical filtration physically removes debris – uneaten food, plant matter, fish waste – from the water using materials like sponges or filter floss. This is the first stage of cleaning. Chemical filtration uses activated carbon to absorb impurities and toxins, improving the water’s clarity. It's important to note that activated carbon needs replacing regularly as it becomes saturated with these substances. Biological filtration is arguably the most important part, and relies on beneficial bacteria colonising a filter media – usually ceramic rings or bio-balls – where they convert harmful ammonia and nitrite into less toxic nitrate. This process requires an established ‘cycle’ before you introduce fish; we'll come back to this shortly. The pump provides the flow of water through the filter, ensuring everything works efficiently. Different pumps deliver different flow rates measured in litres per hour (LPH). A higher LPH generally means more effective filtration, but too much flow can be stressful for delicate fish species.

When selecting a pump and filter, pay close attention to its flow rate. This is expressed in Litres Per Hour (LPH) and indicates how quickly the water is circulated through the system. For small tanks (up to 60 litres), an LPH of around 200-400 is usually sufficient. Larger tanks will need a higher flow rate, aiming for at least 10-20 LPH per gallon. Don’t be overly concerned with extremely high flow rates initially; it's far more important to ensure the pump doesn't create a turbulent current that could stress your fish. The filter itself isn’t just about removing waste – it also provides surface agitation, which is vital for oxygenating the water. This happens as the water flows through the filter media, increasing contact with air and helping your fish breathe properly.

The ‘cycling’ process deserves particular attention. Before adding any fish, you need to establish a colony of beneficial bacteria within the filter. This takes approximately 4-8 weeks. You can achieve this by adding a small amount of ammonia (available from aquarium suppliers) to the tank and monitoring the water parameters with test kits. The bacteria will consume the ammonia, converting it into nitrite and then nitrate. Regularly testing your water for ammonia, nitrite, and nitrate is crucial during this period. Once you consistently have zero ammonia and nitrite readings, and a measurable level of nitrate, you've successfully completed the cycle. You can speed up this process slightly by using commercially available ‘starter bacteria’ products, but it still requires careful monitoring and testing.

There are different types of filters available, each with its own advantages. Internal filters sit inside the aquarium tank and are relatively compact and easy to maintain. Hang-on-back (HOB) filters attach to the outside of the tank and provide good filtration for smaller tanks. Sponge filters – often used in combination with air pumps – offer gentle filtration and aeration, suitable for delicate fish species like neon tetras. Finally, canister filters are more complex and typically larger, offering superior filtration capacity but requiring more maintenance. For a beginner, an internal filter or HOB filter is generally the most straightforward option.

Finally, while things like pre-filters (fine sponges designed to trap large particles) and additional media packs can seem beneficial, they're often not essential for a first setup. Focus on a good quality filter with sufficient capacity for your tank size and prioritise establishing that biological cycle. You can add these supplementary items later once you’ve gained experience and understand the specific needs of your fish. Don’t feel pressured to buy the most expensive model – a reliable, well-rated filter at the lower end of the price range will often perform just as effectively with proper maintenance.