Internal aquarium filters: types, features, best models

If you want your aquarium to be not just a pretty picture, but a healthy and balanced ecosystem, you can't do without a good filter. Internal filters are a popular and convenient choice for many aquarists, especially beginners and those with medium and small tanks. They are compact, easy to install and maintain, and do an excellent job of their main task: cleaning the water of visible dirt and, more importantly, maintaining biological balance.

But “internal filter” is a general term for devices that can work in different ways. Some simply push water through a sponge, trapping debris. Others—more advanced models—combine several stages of purification: mechanical, biological, and chemical. Understanding these differences is key to choosing the right helper for your underwater world.

In this article, we will look at the different types of internal filters, how they differ from each other, and what to look for when buying one. We will also look at specific models that have earned the trust of aquarists. This will help you make an informed choice and provide your fish with crystal clear and safe water.

Internal filters: purpose, types, features

The simplest internal filter consists of a pump and a sponge. It is used to clean the aquarium of large debris particles and to mix the water, which helps to saturate it with oxygen necessary for the life of fish. Many models of internal filters are equipped with built-in aerators and water mixing speed regulators. The lower layers of water are constantly mixed with the upper layers.

Mixing the water allows you to maintain the same temperature in all layers of the aquarium. Carbon dioxide is removed from the water surface more quickly. Simple models of internal filters can only be used for aquariums with a small number of hardy fish such as guppies. In other aquariums, internal filters with biofiltration are used.

Biofilters include devices in which water is passed through a substrate containing bacteria.

Such models do not affect the chemical processes taking place in the aquarium. They improve hygiene in it and, most importantly, prevent the appearance of ammonia, which causes the death of aquarium fish.

How it works

Most internal aquarium filters have a cylindrical body with slots on the surface. These are necessary for drawing water into the device. Inside the body, there are several layers of filter material. Most often, this is elastic polyurethane foam. Water is drawn into the device by a pump attached to the body.

The water filling the aquarium passes through the filter material under pressure and, after getting rid of foreign impurities, returns to the aquarium. Microorganisms that produce biological water purification accumulate in the filter cells. They break down organic compounds into inorganic substances.

Types of internal aquarium filters

Devices are classified according to various criteria:

• performance;
• water filtration capabilities;
• the availability of additional options, etc.

Internal filters are classified according to the method of cleaning the water in the aquarium:

• mechanical;
• chemical;
• biological;
• aeration;
• mixing water masses.

Devices can combine various functions. Filters are classified according to their main function.

Depending on the type of design, the devices are divided into filters:

Advantages and disadvantages of internal aquarium filters

The main advantage of these devices is their compactness. They are easy to maintain and do not require water to be supplied via hoses and pipes. A major disadvantage of internal filters is that they can only be used in aquariums with a volume of up to 200 liters. Filters with air compressors have low performance.

Internal filters are most often used in aquariums for mechanical water purification. Other types of filtration are carried out using external devices. When immersed in an aquarium, internal filters require camouflage. Inside the aquarium, they are attached to its back wall with suction cups.

Internal filters are simple and effective aids for maintaining water purity in an aquarium, especially convenient for beginners and small tanks. They are installed directly in the aquarium, take up little space, and handle mechanical, biological, and chemical cleaning. The main types are sponge, cartridge, and combination filters, and the choice depends on the size of the aquarium, the number of fish, and the type of plants. Among the popular models are reliable and quiet filters from trusted brands that are easy to clean and do not require complex maintenance. The main thing is to choose a filter with the right power and not forget to service it regularly.

Best internal filters

The rating is based on reviews from aquarists.

Eheim Pickup 200 filter

Country of manufacture: Germany. The model is designed for small aquariums with a volume of up to 200 liters. The Eheim Pickup 200 housing is made of plastic. The upper part can be easily removed together with the filter sponge. This makes it easy to replace the cartridge. Water is sucked in at the bottom of the housing.

This model is equipped with a spray bar that allows you to adjust the direction of the water jets passing through the filter. If necessary, activated carbon cartridges can be used in the device. They are used to purify water when starting a new aquarium. The Eheim Pickup 200 can be installed in saltwater and freshwater aquariums.

Specifications:

• filtration type: mechanical and biological.
• filter capacity – up to 570 l/hour.
• dimensions: 70 x 280 x 180 mm.

Advantages:

• quiet operation;
• good build quality;
• excellent filtration;
• reliable suction cups;
• easy to clean.

Tetra EasyCrystal 100

Country of manufacture: China. The model is designed for small aquariums with a volume of 5 to 15 liters. Along with cleaning the water in the aquarium, Tetra EasyCrystal 100 creates the biological balance necessary for a healthy environment.

The product includes special mounts for installing the filter in aquariums with flat and convex glass, as well as replaceable cartridges. They are easy to insert into and remove from the filter. After filtering the aquarium water, bacteria are added to it, which convert nitrite, which is toxic to fish, into nitrate.

Specifications:

• filtration type – mechanical, chemical, and biological;
• filter capacity: 100 l/hour.
• dimensions – 85x85x160 mm.

Advantages:

• suitable for aquariums of various configurations.
• good power;
• quiet operation.
• reliable operation.
• easy maintenance.

Juwel Bioflow 3.0

Country of manufacture: Germany. The model is designed for saltwater aquariums with a volume of up to 260 liters. The product includes a pump that is optimally matched to the water flow rate.

The filter materials are located in convenient baskets. Chemical impurities are removed from the water using a charcoal sponge.

Specifications:

• filtration type: mechanical, chemical, and biological.
• filter capacity – 600 l/hour;
• dimensions: 155x102x417 mm.

Advantages:

• includes sponges for colonizing bacteria that actively purify the water;
• good performance;
• high power;
• reliable construction;
• easy to maintain.

AQUAEL FAN FILTER plus

Country of manufacture – Poland. The best-selling model of this brand. Designed for aquariums with a volume of up to 60 liters. The device is popular with aquarists because of its ease of maintenance and installation. It makes sense for novice aquarists to start with this filter. The filters perform two functions: they purify the water in the aquarium and saturate it with oxygen.

The product includes a special aeration filter. The device is installed on the rear inner wall of the aquarium using a holder equipped with suction cups. The AQUAEL FAN FILTER plus has a function to adjust the water flow rate at the filter outlet. The flow direction adjustment range is 75°.

Features:

• filtration type – mechanical;
• filter capacity – 260 l/hour;
• dimensions – 190x60x90 mm.

Advantages:

• reliability;
• quiet operation.
• low cost;
• good water purification and aeration quality.

Disadvantages:

• cannot be used for saltwater aquariums;
• gets dirty quickly.

BARBUS WP-300F

Country of manufacture: China. The model is designed for small aquariums with a volume of up to 20 liters. The device has optimally balanced functionality. Water filtration is carried out using a sponge.

Thanks to the “Water Flute” system, the water is evenly distributed throughout the aquarium after filtration. The material of manufacture is metal and plastic. The product includes: replaceable nozzles for filtration, sprinkling, aeration, and water circulation.

Characteristics:

• filtration type: mechanical
• filter capacity – 150 l/hour;
• overall dimensions: 130x80x60 mm.

Advantages:

• reliable construction;
• low cost
• ease of operation and maintenance.

Disadvantages:

• increased noise level during operation.
• replacement sponges are not always the right size.

JUWEL Bioflow 8.0 1000 l/hour

Country of manufacture: Germany. The model is designed for aquariums with a volume of 350 to 500 liters. The filter has an increased volume (8 liters). The product is attached to the inner wall of the aquarium using a special silicone adhesive, which is included in the device kit.

The filter has a function for adjusting the speed of the water flow. The manufacturer provides the option of parallel installation of a water heater of the same brand.

Features:

• filtration type: mechanical, chemical, and biological.
• filter capacity: 1000 l/hour.
• dimensions: 223 x 530 x 155 mm.

Advantages:

• high performance;
• possibility of installing additional components;
• dual-flow filter;
• effective purification of water from all types of contaminants.
• reliability.
• no hose connections.

Disadvantages:

• high cost
• large dimensions.

Expert advice

Vasily Ignatiev

Aquarist

When buying internal filters for your home aquarium, you need to pay attention to their fillers. Fine- and coarse-pored sponges, as well as carbon absorbents, are considered the best.

Denis Shifrin

Employee of the Aqua company

When choosing an internal filter for an aquarium, it is necessary to take into account the required depth of immersion. The height of the water level above its upper point should not be less than 2 cm.

Water purification and aeration in an aquarium are an important part of aquarium keeping. The correct choice and installation of internal filters determines how long the fish in the aquarium will live.

As you can see, choosing an internal filter is not that difficult. The main thing is to start from the size of your aquarium and its inhabitants. For a small aquarium with shrimp or small fish, a simple airlift filter will suffice. For a medium-sized aquarium with ordinary fish, a pump filter with a sponge is ideal. And for demanding or large fish, it is better to look for models with several stages of purification.

Don't go for the most expensive model. Often, a simple and reliable design will serve you for years. Pay attention to ease of maintenance: the sponge will need to be washed regularly. And don't forget about noise levels if the aquarium is in your bedroom.

Remember that the filter is the heart of your aquarium. When chosen correctly, it will create crystal clear water and a healthy environment for your pets. This, in turn, will save you time on maintenance and give you a lot of joy from observing a beautiful and stable underwater world.