Troubleshooting Common Aquarium Problems

Aquariums can be wonderfully relaxing, but every aquarist sooner or later encounters cloudy water, algae explosions, sick fish or noisy filters. Instead of giving up, it is worth learning how to read what the tank is “telling” you and how to react step by step. In this guide we will go through the most common aquarium problems, show their root causes and proven solutions. MB Store supports these efforts by offering carefully selected aquariums and matching equipment so you can build a stable, beautiful and healthy underwater world.

Understanding the aquarium as a living ecosystem

An aquarium is not only glass, water and fish. It is a dynamic ecosystem in which biological, chemical and mechanical processes constantly interact. Most problems arise when this balance is disturbed. Too many fish, too rare water changes, inappropriate filtration or poorly selected lighting quickly become visible in the form of turbidity, algae or diseases.

The basis of a healthy aquarium is the so-called biological filtration. Beneficial bacteria that live in the filter media, substrate and decorations convert toxic ammonia from fish waste into nitrites and then into relatively safe nitrates. This process, known as the nitrogen cycle, is the heart of every tank. If the cycle is not yet stabilized or has been disrupted, fish are exposed to stress and poisoning, and the water quickly loses clarity.

Another key element is water parameters such as pH, hardness, temperature and the concentration of nitrogen compounds. Each group of fish and plants has specific requirements, and longer-term deviations from the optimal range always lead to weakening of organisms and increased susceptibility to disease. Regular testing using simple tests allows you to react before the problem becomes visible to the naked eye.

At MB Store you will find complete aquariums, efficient filters, heaters and modern LED lighting that help maintain balance. Properly selected equipment makes everyday maintenance easier and significantly reduces the likelihood of serious failures or fish losses.

Cloudy water and unpleasant odours

Cloudy water is one of the first difficulties faced by new aquarists. It may appear milky-white, yellowish or greenish, and each of these colors indicates a different source of the problem. Although turbidity looks alarming, in many cases it is a natural stage of maturation of the aquarium and can be brought under control without drastic measures.

Milky turbidity is often caused by a bacterial bloom. When a new tank is set up or the filter is thoroughly cleaned, beneficial bacteria must rebuild their population. Until they stabilize, the water may appear cloudy. The basic mistake is changing all the water or excessive cleaning of the filter, which constantly resets the biological balance. Instead, it is better to carry out moderate water changes and be patient. Adding a biological activator with live bacteria, available, for example, at MB Store, will significantly speed up this process.

Yellowish water is usually the result of tannins released from roots, leaves or other decorations of natural origin. For many species of fish this is not a problem and even creates conditions similar to those in nature. However, if you prefer crystal clear water, it is worth soaking new decorations before placing them in the tank and using activated carbon or special resins in the filter. Activated carbon binds colouring substances and many organic contaminants, restoring transparency.

Green turbidity almost always points to microscopic algae suspended in the water column, known as green water. The causes are too long or too intense lighting, an excess of nutrients (mainly nitrates and phosphates) and an unstable biological balance. Limiting lighting to about 6–8 hours a day, reducing feeding, and performing several larger water changes in a row helps. UV sterilisers are also very effective, quickly clearing water of free-floating algae without harming the fish.

An unpleasant smell is a clear sign that too much organic matter is decomposing in the tank. Overfeeding, a thick layer of uneaten food in the substrate, decaying leaves or dead fish always lead to spoilage. Regularly vacuuming the bottom, removing plant debris and controlling the amount of food will prevent such situations. If the smell appears suddenly, it is worth immediately checking whether all inhabitants of the aquarium are alive and whether the filter is working properly.

Algae outbreaks and how to control them

Algae are a natural component of every aquatic ecosystem, but in the aquarium they can quickly get out of control. They appear on glass, leaves, decorations and substrate, making the tank look neglected. Each type of algae has its own causes and preferred conditions, so recognising which one you are dealing with facilitates effective action.

Brown algae most often attack new aquariums, especially those with weak lighting. They form a dusty or velvety coating on glass and decorations. They disappear when the tank matures and the lighting intensity is increased. Regular cleaning of glass with a scraper and rinsing decorations under running water help keep them under control. The presence of live plants and appropriate light duration effectively limits their growth.

Green spot or film algae appear on glass, stones and slow-growing leaves. Their cause is usually too strong light in relation to the amount of nutrients used by plants. It is worth checking the duration of lighting and making sure that the tank is not additionally illuminated by direct sunlight. Introducing algae-eating species, such as certain shrimps or snails, may support mechanical cleaning but will not replace proper care.

The most troublesome are filamentous and brush algae, which form long threads or dark, fluffy tufts on plants and decorations. They often appear in tanks with unstable CO₂ levels, irregular fertilisation or an imbalance between phosphates and nitrates. The first step is always to stabilise the basic parameters: constant lighting time, regular water changes, well-functioning filtration and moderate feeding. Removal of the most infested leaves and decorations reduces the biomass of algae and speeds up the improvement.

It is important not to fight algae only with chemicals. Algaecides may bring quick visual relief, but if the cause persists, the problem will come back, often stronger. Better results are achieved by a long-term approach: strongly growing plants competing with algae for nutrients, a properly set photoperiod, and a carefully selected fertilisation plan. MB Store offers not only lighting and fertilisers but also practical accessories such as scrapers, hoses and brushes that make regular cleaning easier.

Fish health issues and stress

Healthy fish are active, have vivid colours, willingly accept food and show natural behaviour. When something is wrong, they hide, breathe rapidly, rub against decorations or float near the surface. Many diseases are a direct consequence of stress caused by poor conditions. Recognising early symptoms allows you to intervene before the disease spreads throughout the aquarium.

The most common causes of stress include unsuitable water parameters, sudden temperature changes, overcrowding and aggressive tank mates. For example, keeping fish that require soft, acidic water together with species preferring hard, alkaline water leads to chronic discomfort. Similarly, a heater that is too weak or lacks a thermostat causes dangerous temperature fluctuations between day and night. Good quality heaters and precise thermometers available at MB Store help maintain stable conditions tailored to the needs of specific species.

Among frequently encountered diseases is ich, manifested by small white spots on the body and fins. It often occurs after introducing new fish without quarantine. Treatment requires raising the water temperature in accordance with the medicine manufacturer’s instructions and using a dedicated preparation. During treatment it is necessary to increase aeration, because higher temperature reduces the solubility of oxygen in water. Quarantine of new fish in a separate tank for at least two weeks significantly reduces the risk of introducing pathogens.

Fin rot, fungal infections and bacterial diseases usually develop in polluted water with high content of organic matter. Regular water changes, efficient filtration and avoiding overstocking are the best prevention. When symptoms appear, it is necessary to quickly identify the cause and, if needed, use appropriate medications. It is important to follow the dosage and duration of treatment; ending therapy too early often causes a recurrence of the disease in a more resistant form.

Nutrition plays a crucial role in immunity. Monotonous feeding with only one type of dry food weakens fish over time. A varied diet that includes quality flakes or granules, frozen or live foods and specialised plant-based products for herbivorous species improves condition and coloration. MB Store offers feeds tailored to different groups of fish so you can easily compose a balanced menu.

Equipment failures and technical challenges

Even the best planned aquarium will not function properly without efficient equipment. A filter that loses performance, a heater stuck in the on position or flickering lighting can quickly lead to serious problems. Regular inspection and maintenance significantly extend the life of devices and protect fish from sudden crises.

The filter is the heart of the system, responsible for mechanical cleaning of water and housing of beneficial bacteria. A common mistake is rinsing filter media under hot tap water or thoroughly cleaning the entire interior too often. Chlorine from tap water and high temperature kill bacteria, and the tank must go through the cycle again. Instead, media should be gently rinsed in water taken from the aquarium during a water change. If the flow decreases, check for clogging of hoses, impeller and intake grates.

Heaters with thermostats usually work reliably, but it is still worth regularly monitoring the temperature with an independent thermometer. If the reading differs significantly from the value set on the heater, the device may be damaged. A stuck-on heater can overheat the tank, while a non-functioning one will expose fish to hypothermia. In larger aquariums, many aquarists use two weaker heaters instead of one strong one to increase safety in case of failure.

Modern LED lighting is energy-efficient and offers a wide range of colours, but incorrectly selected power or operating time is a frequent source of algae and plant problems. A heavily lit but poorly planted tank almost always becomes an algae farm. It is better to start with a moderate photoperiod and gradually adjust it depending on plant growth and algae presence. Timers or automatic controllers simplify maintaining regularity, which is very important for the entire ecosystem.

MB Store supplies a wide range of reliable filters, heaters, air pumps and LED lamps from trusted manufacturers. By choosing equipment from one place, you gain the certainty that all elements will work together harmoniously and that you will find easily compatible accessories and spare parts if needed.

Overfeeding, overstocking and maintenance mistakes

Many aquarium troubles are not caused by complicated chemical processes but by simple human habits. Excessive numbers of fish, too frequent interference and overfeeding are classic mistakes made by beginners and sometimes even experienced aquarists.

Overstocking leads to a rapid accumulation of waste and overloading of the filter. Even the best biological filtration has its limits; if the number and size of fish exceed the capacity of the tank, ammonia and nitrite levels will rise. When planning stocking, consider the adult size of fish, not only the dimensions of juveniles sold in the shop. It is better to have fewer, well-kept specimens than a crowded and constantly problematic aquarium.

Feeding is another area where good intentions cause harm. Food lying on the bottom and decomposing between plants or in the substrate is a constant source of pollution and nutrients for algae. A rule of thumb is that fish should eat the given portion in a few minutes. If food remains, the portion is too large. It is worth observing fish behaviour; some species are slow and timid and may need targeted feeding in a calm part of the tank.

Maintenance mistakes include both neglect and excessive zeal. Rare water changes result in a slow but steady deterioration of quality, while very large, sudden water replacements can shock fish and beneficial bacteria. For most tanks, changing 20–30% of water once a week or every two weeks is optimal. During this procedure, it is good to vacuum the bottom, gently clean the glass and check the condition of the equipment. Using dechlorinating conditioners protects bacteria and fish from chlorine and heavy metals present in tap water.

Interference in the arrangement of decorations, the substrate and plants should also be done with moderation. Frequent moving of elements may cause stress to fish and clouds of sediment rising from the bottom. Planning the layout carefully at the beginning saves a lot of work in the future. In MB Store you will find not only aquariums and technical devices, but also a wide selection of substrates, stones, roots and decorations that allow you to create a stable, aesthetic layout that does not require constant reconstruction.

How MB Store can support your aquarium journey

Building a stable and beautiful aquarium is a process that combines knowledge, appropriate equipment and regular observation. MB Store accompanies aquarists at every stage of this path, offering complete sets for beginners and advanced hobbyists, as well as individual components for personalised configurations.

In the offer you will find aquariums of various sizes, from compact tanks for a desk to spacious sets for the living room. Matching filters, heaters, lighting and covers make it easy to choose a coherent set in which each element has the right performance for the planned volume. Additionally, you can purchase substrates, decorative stones, roots and plants that not only decorate but also support the biological balance.

For ongoing maintenance, MB Store offers a wide range of water tests, conditioners, fertilisers and specialised feeds. Thanks to them you can quickly diagnose problems with parameters, stabilise the nitrogen cycle and provide fish with a varied, nutritious diet. Practical accessories such as siphons, cleaning magnets, sieves and nets facilitate everyday care and make it less time-consuming.

When choosing products, it is worth consulting the descriptions and recommendations prepared for specific types of aquariums: community, plant-based, biotope or shrimp tanks. MB Store focuses on solutions that are proven and compatible with each other, so that customers can avoid unnecessary experimentation and enjoy a healthy underwater world for a long time.

FAQ

How often should I change the water in my aquarium?
For most community aquariums, a water change of 20–30% once a week is a safe and effective routine. Regular partial changes remove nitrates and accumulated organic waste without shocking fish or beneficial bacteria. In heavily stocked or small tanks you may need slightly more frequent changes, always with dechlorinated water of similar temperature.

Why do my fish keep dying after I set up a new tank?
Early fish deaths in a new aquarium are usually caused by an uncycled filter and toxic ammonia or nitrite spikes. Before adding fish, the tank should run for several weeks to build up a stable bacterial population. Using bacterial starters, testing water and introducing only a few hardy fish at first helps prevent losses and allows the system to stabilise safely.

What can I do to prevent algae from taking over my tank?
To limit algae, balance three key factors: light, nutrients and plant growth. Avoid placing the aquarium in direct sunlight, set a stable photoperiod of 6–8 hours and do not overfeed fish. Regular water changes, strong plant growth and moderate fertilisation direct nutrients to plants instead of algae. Mechanical cleaning of glass and decorations completes this long-term strategy.

How do I know if my filter is strong enough?
A properly sized filter should circulate the entire aquarium volume several times per hour, typically 4–8 times depending on stock and setup. If debris accumulates quickly, water is cloudy or fish stay near the surface seeking better oxygen, the flow may be insufficient. Upgrading to a more powerful filter or adding additional circulation often improves water clarity and fish comfort.

Is an air pump necessary if I already have a filter?
An air pump is not always essential, because many filters already provide surface agitation and gas exchange. However, in heavily stocked tanks, warm water, or during medication use, extra aeration is very helpful. Rising air bubbles increase oxygenation and support beneficial bacteria. It is a simple, inexpensive safeguard that can be critical in emergency situations.