Choosing the Right Filtration System for Your Aquarium
Creating a healthy aquarium is about much more than adding water and fish. At the heart of every stable tank stands the filtration system, responsible for keeping the environment clean, clear and safe for all inhabitants. Choosing the right filter is one of the most important decisions you will make as an aquarist, whether you are setting up your first nano tank or upgrading a large, heavily stocked aquarium. On the MB Store blog we want to help you understand how filtration works and how to select a solution that matches your aquarium, your livestock and your daily routine. MB Store offers complete aquariums as well as dedicated equipment, so you can easily build a well‑matched system from the very start.
Understanding the three pillars of aquarium filtration
Every aquarium filter, regardless of its size and shape, performs three key tasks: mechanical, biological and chemical filtration. Knowing what each of these processes does will help you judge whether a given filter model is well designed and how to configure it for your particular tank. When you look at filtration this way, you no longer see only “a device that moves water”, but a complete system that supports the miniature ecosystem living behind the aquarium glass.
Mechanical filtration is the most intuitive to understand. Water passes through sponges, pads, floss or other media that physically trap suspended particles: plant debris, leftover food, fish waste, fine dust in the water column. This is what makes the water look visually clear and prevents large pieces of dirt from decomposing directly in the tank. The effectiveness of mechanical filtration depends on how much water the filter processes per hour, how large the mechanical media area is, and how often you clean or replace them. In practice, it is better to use several layers of different density rather than one extremely fine pad that clogs quickly and slows the flow.
Biological filtration is the core of long‑term stability in any aquarium. On porous surfaces inside the filter, colonies of beneficial bacteria grow. These micro‑organisms convert toxic ammonia, produced by fish and decomposing organic matter, into nitrite and then into relatively safer nitrate. Without efficient biological filtration, even a small feeding mistake or a dead leaf stuck in a corner could cause a dangerous spike in toxins. Biological media include ceramic rings, bio‑balls, sintered glass, lava rock and specialised blocks; their key feature is enormous surface area combined with good water flow and oxygen availability.
Chemical filtration uses specific materials to remove dissolved substances that cannot be caught mechanically and are not handled directly by nitrifying bacteria. Activated carbon adsorbs dyes, medication residues and some organic compounds, while resins can bind phosphates, heavy metals or nitrite. Chemical media are powerful tools but must be used thoughtfully. They have limited capacity and need regular replacement; otherwise, they may start leaching captured substances back into the water. Many experienced aquarists run chemical media only temporarily, for example after a treatment or when combating an algae bloom.
When you choose a filtration system, you are actually choosing how these three components will be combined. A small internal filter may offer basic mechanical and biological filtration in a compact form, while a large canister filter can provide extensive mechanical pre‑filtration, a large volume of biological media and optional chemical cartridges. Understanding these roles helps you look beyond marketing slogans and evaluate whether a particular model truly fits the needs of your aquarium and its inhabitants.
Matching filtration type to aquarium size and livestock
No single filter design is ideal for every aquarium. A heavily planted nano shrimp tank, a community aquarium with schooling fish and a predator tank with large cichlids will each place very different demands on the filtration system. To choose well, you should consider several factors simultaneously: volume of the aquarium, type and number of inhabitants, presence of plants, feeding habits, as well as how much noise, maintenance and equipment visibility you are prepared to accept in your living space.
Internal filters are popular for smaller aquariums and beginner setups because they are relatively inexpensive, simple to install and easy to access. They sit inside the tank and usually offer a combination of sponge and sometimes a small compartment for additional media. This makes them suitable for lightly to moderately stocked freshwater aquariums up to about 100 litres. Their main limitations are modest filter volume and the fact that, being inside the tank, they occupy space and can be visually intrusive. However, in nano aquaria for shrimp, bettas or small fish, a carefully chosen internal filter with a gentle flow can provide reliable basic filtration with minimal complexity.
Hang‑on‑back filters (often called HOB filters) are mounted on the rim of the tank, drawing water from inside and returning it in a cascade. They offer more room for media than many internal models and are easy to maintain because you can access them from outside the aquarium. They are an excellent choice for medium‑sized tanks where you want good performance without diving into more advanced equipment. For aquarists who value quiet operation, it is worth checking the construction of the impeller and the way water enters the filter; some models are nearly silent, while others produce a characteristic trickling sound that may or may not be desirable in a bedroom or office.
External canister filters are often considered the gold standard for larger and more demanding setups. Positioned under or next to the aquarium, they can offer a very large volume of filter media, flexible configuration and powerful yet adjustable flow. This makes them an outstanding solution for heavily stocked community tanks, cichlid aquariums and large planted aquaria where strong biological filtration is essential. Because they sit outside the tank, they do not disturb the aquascape visually and reduce clutter inside the glass. Modern canisters sold by specialised suppliers such as MB Store often include quick‑disconnect valves, priming aids and carefully designed baskets that simplify cleaning and allow you to tailor the internal layout to your goals.
For advanced marine systems and high‑end freshwater displays, sump filtration provides an entirely different level of flexibility. A sump is a separate tank, usually located in the cabinet below, connected to the main aquarium through overflow and return plumbing. Water continuously circulates between the two, and the sump can house large volumes of biological media, mechanical pre‑filters, heaters, skimmers and other equipment. This approach is especially appreciated in marine reef aquariums, where stable parameters and heavy biological loads demand robust solutions. While more complex to set up, a sump offers unmatched potential for expansion and hidden equipment, leaving the display tank clean and natural‑looking.
When you evaluate filter types, consider also the sensitivity of your livestock to current and noise. Some species, like bettas and certain dwarf cichlids, prefer calm areas and can be stressed by strong surface agitation. Others, such as riverine fish, enjoy swimming against a current and benefit from vigorous circulation. By choosing a filter that allows you to direct or diffuse the outflow, you can create zones within the tank that suit different species. MB Store’s range of filtration equipment covers compact internal filters, efficient HOB units, powerful canisters and components for sump systems, so you can align technology with the natural behaviour of your fish and invertebrates.
Flow rate, media volume and practical sizing rules
Once you have a general idea of the type of filter you want, the next step is to match its capacity to your aquarium. Manufacturers usually specify maximum tank size and flow rate in litres per hour. While these figures are a useful starting point, they do not tell the whole story. Two filters with identical flow ratings can offer very different real‑world performance depending on how much media they hold, how easily they clog and how efficiently water is distributed through the internal chambers.
As a rule of thumb, for freshwater aquariums you want a filter that can circulate the entire water volume about four to six times per hour. For example, a 100‑litre tank will benefit from a filter with a real flow of 400–600 l/h. In heavily stocked or messy setups, such as goldfish or large cichlids, aiming for even higher turnover can be helpful. Marine aquariums often require stronger circulation overall, but part of that is provided by dedicated wave makers and powerheads, not only by the filter or sump. Plant‑focused aquaria sometimes use moderate flow to avoid excessive CO₂ loss, yet even there, sluggish water can lead to dead spots and accumulation of waste.
Media volume is just as important as flow. A small device that pushes water quickly but has minimal space for biological media will not support stable bacterial populations. When comparing filters, look beyond the headline flow number and check how many litres of media they can hold. Larger sponges and baskets of ceramic rings or sintered glass provide the house in which beneficial bacteria live. MB Store offers detailed descriptions of filter models, including media capacity and recommended aquarium sizes, which helps in making informed decisions instead of relying only on optimistic packaging claims.
It is also necessary to consider that the actual flow in a working filter is lower than the maximum indicated by the manufacturer. As media become colonised by bacteria and capture particles, resistance to water flow increases. Vertical height between the filter and the aquarium also matters for external systems; the higher the lift, the more the effective flow can drop. That is why choosing a slightly oversized filter is often wise, particularly for tanks that will evolve from a few small fish into a densely stocked community over time.
Practical sizing should not ignore maintenance reality. A filter that quickly becomes clogged demands frequent intervention, which can be inconvenient and may disturb the aquarium more than necessary. By selecting a model with generous pre‑filtration, you can prolong intervals between deep cleanings while still preserving strong mechanical performance. Some aquarists use two filters on one tank: one focused on mechanical tasks and the other on biological stability. This redundant approach reduces the risk that a single failure will compromise the entire system and allows alternating maintenance between units.
Designing a smart media layout inside your filter
Even the best filter body is only as effective as the media placed inside. Thoughtful configuration of sponges, ceramics and other materials will significantly influence water clarity and biological stability. Although manufacturers often provide a default arrangement, you can usually improve it with small adjustments. The goal is to ensure that water first passes through coarse mechanical barriers, then through finer layers, and finally through the main biological section, with optional chemical media placed where they will not clog prematurely.
Start with a coarse sponge or pre‑filter pad where water enters the filter. Its job is to capture large debris and protect the downstream media from rapid clogging. Next, use medium and fine sponges or floss to polish the water. Fine floss can remove very small particles that cloud the water, but it saturates quickly, so it is essential to position it where it can be easily removed and rinsed or replaced. Underneath this mechanical section, allocate as much space as possible to true biological media. Their performance depends on surface area, pore structure and the way water flows between pieces. High‑quality ceramics and sintered glass products provide tremendous surface while allowing adequate oxygenation.
Chemical media should be treated as specialised tools rather than permanent necessities. If you decide to use activated carbon, phosphate removers or other resins, place them after the main mechanical stage but before the heart of biological filtration. In this position, they receive relatively clean water, which extends their useful life and prevents rapid saturation. Remember that these materials are consumable; they do not last indefinitely and must be replaced according to the manufacturer’s recommendation or test‑kit results. MB Store stocks a wide selection of advanced media, allowing you to tailor your filter’s interior both to everyday use and to specific tasks such as removing medication after a disease treatment.
When rearranging filter media, be careful not to disturb biological colonies unnecessarily. Cleaning should be done with old aquarium water during a partial water change, never under hot tap water or with detergents, which would kill beneficial bacteria. It is usually enough to gently squeeze sponges and rinse mechanical pads, leaving a portion of the bacterial film intact. Biological media should be cleaned rarely and only if visibly clogged. With an intelligent layout and respectful maintenance, your filter can run for years as a stable, living support system rather than a sterile mechanical device.
Maintenance routines that keep filtration efficient
Even the most sophisticated filter will fail if forgotten under the cabinet for months. Proper maintenance is not about frequent complete overhauls, but about regular, gentle interventions that preserve bacterial life while restoring flow and mechanical clarity. Establishing a simple routine will protect your fish from sudden parameter swings and keep the aquarium attractive without requiring excessive time investment.
The first sign that your filter needs attention is usually reduced flow. If the water return appears weaker than usual or surface agitation decreases, mechanical stages are likely becoming clogged. In most setups, inspecting and rinsing sponges and pads every two to four weeks is sufficient, though heavily stocked tanks may demand more frequent checks. Always prepare a bucket of aquarium water during water changes; use this to squeeze and clean the sponges. This method removes trapped dirt while keeping the majority of bacteria alive, ensuring biological filtration continues to operate effectively.
Deeper maintenance, such as cleaning impellers, hoses and canister chambers, can be performed less often, perhaps every two to three months, depending on conditions. When opening an external filter, avoid changing all media at once. If a replacement is necessary, do it in stages: for instance, half of the sponges one month, the remaining half in the next cycle. This staggered approach prevents drastic reductions in beneficial bacterial populations. After reassembly, check for leaks and ensure the filter is properly primed to avoid air pockets and noisy operation.
Monitoring water parameters complements physical maintenance. Regular testing of ammonia, nitrite, nitrate and, in marine or advanced planted systems, additional parameters such as phosphate, pH and hardness, allows you to see how well your filtration copes with the bioload. A stable reading of zero ammonia and nitrite, with moderate nitrate levels controlled by water changes, indicates that biological filtration is functioning well. If you detect toxic compounds, investigate feeding quantity, stocking density and potential hidden waste in the substrate or decorations, not only the filter itself.
MB Store supports aquarists by offering a wide range of maintenance accessories: hoses, brushes, pre‑filters, replacement sponges and test kits. By planning your filter around easily available consumables, you make it more likely that you will keep up with regular service rather than postponing it because parts are difficult to find. A clean, well‑maintained filter brings peace of mind: you know that your fish swim in safe water, and you avoid sudden, stressful crises that could have been prevented with a few minutes of periodic care.
Integrating filtration with plants, aquascaping and equipment
Filtration does not exist in isolation; it interacts with plants, hardscape and other equipment to create the overall character of an aquarium. In planted tanks, for example, filtration should support both nutrient distribution and gas exchange without stripping too much CO₂ from the water. This means selecting a filter and outflow pattern that generate even circulation but avoid extremely turbulent surface agitation. Glass lily pipes, spray bars and directional nozzles can help shape water movement to favour plant growth while still ensuring adequate oxygen for fish.
The arrangement of rocks, wood and decorations also influences how well filtration performs. Dense hardscape can create dead zones where debris accumulates and water barely moves. When designing an aquascape, it is worth planning from the start where the filter intake and outlet will be placed. Aim to create a gentle circular flow path that sweeps particles toward the intake and avoids stagnant corners. In some layouts, supplementary circulation pumps are helpful to eliminate pockets under overhanging driftwood or behind tall rock structures.
Other equipment such as heaters, CO₂ diffusers and protein skimmers (in marine tanks) should be positioned with filtration in mind. For instance, placing a heater near the filter intake helps distribute warm water evenly, preventing temperature stratification. In sump systems, skimmers and reactors are often located in specific compartments to optimise contact time and performance. MB Store’s offer of aquariums and accessories includes many components designed to cooperate harmoniously: pre‑drilled tanks for sumps, cabinets with appropriate space, and filters whose flow pattern suits both classic community aquaria and sophisticated aquascapes.
Visual integration also matters in a home or office environment. Some aquarists prefer equipment to be as invisible as possible, allowing the interior of the tank to resemble a natural fragment of river or reef. External filters, sumps and carefully chosen intake/outflow accessories help achieve this effect. Others like the technical look of modern equipment and do not mind exposed pipes and reactors. In either case, choosing a filtration system that aligns with your aesthetic preferences increases satisfaction and reduces the temptation to make questionable compromises, such as turning the filter off at night because you dislike the sound or appearance.
Filtration choices for special aquarium setups
Different types of aquaria place unique demands on filtration. A lightly stocked nano tank with live plants, a high‑energy African cichlid aquarium and a marine reef system all require distinctive approaches despite sharing the same basic goals of clarity and stability. Understanding these differences will help you avoid mistakes and select systems that are truly appropriate rather than just minimally adequate.
Nano aquariums, often under 40 litres, present a paradox. Their small volume makes them attractive for desks and small spaces, yet it also means that water parameters can change rapidly. Filters for such tanks must combine gentle flow, sufficient biological capacity and compact size. Sponge filters driven by air pumps are a popular option, especially for shrimp and fry, because they offer soft suction and a large, safe surface where micro‑organisms grow. Small internal or hang‑on filters can also work well if their intake is protected and the outlet diffused. In these miniature systems, stability comes not from brute force but from careful stocking, modest feeding and reliable, modest‑strength filtration.
Heavily stocked freshwater community aquariums and cichlid tanks, by contrast, produce a great deal of waste. Large and active fish consume generous portions of food, and their metabolic output strains biological capacity. Here, robust filtration with high turnover and extensive media volume is essential. External canister filters or sump systems allow the combination of strong mechanical pre‑filtration to catch solid waste, massive biological stages to process dissolved toxins and, if needed, chemical media to control phosphates and tannins. Rock‑heavy cichlid setups from rift lakes also benefit from strong water movement that simulates their natural habitat and prevents detritus from settling between stones.
Marine aquariums, particularly reef systems, raise the bar even higher. Saltwater organisms are often more sensitive to parameter fluctuations than typical freshwater fish. Protein skimmers become a central element of filtration, removing organic compounds from the water before they fully break down. Live rock functions as an extensive biological filter, hosting diverse communities of bacteria and microfauna. Many marine aquarists use sumps not only for mechanical and biological filtration but also as a place for refugia with macroalgae, which absorb nitrates and phosphates. MB Store supplies equipment tailored to marine and freshwater needs, helping you select pumps, skimmers, media and tanks that are compatible and appropriately dimensioned.
There are also specialised setups, such as blackwater biotopes with dark, tannin‑rich water, where the aesthetic goal is not crystalline clarity but a natural, tea‑coloured environment. In these aquariums, filtration must still remove ammonia and nitrite efficiently, yet the aquarist may choose to avoid activated carbon, which would strip tannins and alter the water’s character. Instead, large volumes of biological media and gentle mechanical stages maintain safety while preserving the desired look. This illustrates a broader point: the “right” filtration system is not a universal formula but a solution aligned with the biological and visual goals of each individual aquarium.
How MB Store supports your filtration decisions
Selecting and configuring filtration can seem overwhelming for newcomers, especially when confronted with long lists of specifications, unfamiliar media names and conflicting advice from different sources. MB Store aims to simplify this process by offering not only a wide range of aquariums and filtration equipment but also clear product descriptions, compatibility information and educational materials. By browsing complete sets and component categories, you can see which filters are commonly paired with certain tank sizes and styles, providing a grounded starting point for your own choices.
Because MB Store provides both tanks and equipment, you can plan entire systems rather than collecting random parts. For example, you might choose a pre‑configured aquarium set with a built‑in internal filter appropriate for a beginner community tank, knowing that later you can upgrade to an external canister from the same supplier when your experience and stocking levels grow. Accessories such as intake guards, spray bars, pre‑filters, replacement sponges and advanced media are readily available, making it practical to follow best practices like staged maintenance and thoughtful media layering.
Equally important is the possibility of adapting off‑the‑shelf solutions to your individual needs. Maybe you want extra‑quiet filtration for a bedroom aquarium, or perhaps you are planning a high‑tech planted tank where CO₂ retention is a priority. By understanding the principles described above and combining them with the range of products offered by MB Store, you can build a filtration system that not only meets technical requirements but also fits your personal lifestyle and aesthetic expectations. In this way, filtration stops being an intimidating necessity and becomes a tool that empowers creative, responsible aquarium keeping.
FAQ
How often should I clean my aquarium filter?
Maintenance frequency depends on stocking and filter type, but in most home aquariums mechanical media need rinsing every 2–4 weeks. Clean sponges and pads in removed aquarium water, never under hot tap water, to preserve bacteria. Deep cleaning of canisters, hoses and impeller chambers can be done every few months, always avoiding changing all media at once.
Do I really need biological media if I have plants?
Live plants help absorb nitrogen compounds, yet they cannot replace stable bacterial colonies living in filter media. Biological media provide a huge surface for nitrifying bacteria that keep ammonia and nitrite at zero even when plant growth slows. Combining strong biological filtration with healthy plants offers redundancy and greater safety for fish and invertebrates.
Is a bigger filter always better for my aquarium?
Oversizing a filter for extra biological capacity and longer maintenance intervals is usually beneficial, but only if you can adjust the flow to avoid stressing fish. Very strong current may disturb long‑finned species or uproot plants. Use spray bars or directional outlets to diffuse powerful filters, balancing capacity, circulation and comfort for your livestock.
When should I use activated carbon or other chemical media?
Chemical media are most useful in specific situations, such as removing medication after treatment, clearing water discoloured by dyes or controlling excess phosphates. They have limited capacity and must be replaced regularly. For everyday use in many freshwater tanks they are optional; stable biological filtration and regular water changes usually cover basic needs well.
Can I turn off my filter at night to reduce noise?
Switching the filter off for hours is risky. Without flow, oxygen drops inside the media and beneficial bacteria can die, potentially releasing toxins when restarted. If noise is a problem, consider a quieter model, replace worn impeller parts or place soft pads under the filter. Continuous operation is one of the foundations of a safe aquarium.
