Which filter to choose for your aquarium?

Choose your filter based on the actual tank volume and the animals, then check the flow rate. Sponge or air filter for shrimp and fry, internal filter for a small, lightly stocked tank, external filter for a large tank or big fish. As a guideline, aim for about 3 times the tank volume per hour, and 5 times for fish that produce a lot of waste.

The four types of filters

All filters do the same job: retain waste and house the bacteria of the nitrogen cycle. Our article on the filtration mechanism explains it in detail. What distinguishes them is their location, their volume of filter media, and their maintenance.

• Sponge filter. A simple sponge, with a small pump or air. Its fine surface does not suck up small animals.
• Air filter. It connects to an air pump. The air circulates the water through the media and oxygenates at the same time. Its current remains gentle. Our guide choosing an air pump will help you with the connection.
• Internal filter. Compact, economical, it sits in the tank. It takes up space in the decor and its volume remains limited.
• External filter. It is placed next to or under the stand and connected by hoses. It offers more media volume, is cleaned less often, and frees up space in the tank. It requires more space around it and a higher budget.

Choosing according to your tank

Two questions usually make the difference. The first concerns the animals. Goldfish or large cichlids produce much more waste than small schooling fish, and an external filter is therefore required. Shrimp or fry, on the contrary, require a protected water inlet and a gentle current.

The second concerns the volume. As a guideline, the Zoanthus guide places the internal filter up to about 150 to 200 liters, the air filter up to about 50 liters, and the external filter beyond. Nothing prevents installing an external filter on a small tank: very compact ones exist.

Also think about the use. A planted aquarium keeps its CO2 better when the surface is not too agitated: a variable flow rate or a directional water outlet are then useful. If you are looking for the best location, see where to put the pump of an aquarium.

Sizing the flow rate

Our article what filtration flow rate for an aquarium details the reasoning. To choose, keep three reflexes in mind.

1. Calculate the actual volume. Sand, rocks, and wood reduce the available water. Our method for calculating the volume of an aquarium gives you the starting figure.
2. Multiply according to the animals. About 3 times for small fish, 5 times for goldfish or large cichlids. Never choose a flow rate less than or equal to the tank volume.
3. Keep a margin. The displayed flow rate is a maximum, generally measured empty. In the tank, with media and hoses, it will be lower, and it drops even further when the filter gets dirty.

Some guidelines by size

The data below comes from our store product sheets. Check the exact reference before ordering: the volume indicated by the manufacturer assumes a reasonable population.

• Up to 60 liters: Sera Fil 60, internal filter of 380 l/h. Oase BioPlus 50, internal filter of 350 l/h up to 50 liters.
• From 20 to 80 liters, with shrimp: JBL CristalProfi M Greenline, sponge filter.
• Up to 120 liters: Sera Fil 120, internal filter of 700 l/h. JBL CristalProfi e402, external filter of 450 l/h for 40 to 120 liters.
• From 60 to 200 liters: JBL CristalProfi e702, external filter.
• Up to 350 liters: Oase BioMaster 350, external filter of 1,100 l/h, with a pre-filter accessible without dismantling the entire filter.

For an air filter, the SF Bio Air Disk S combines sponge and ceramic media. It connects to an air pump, which should be planned separately.

Buying mistakes to avoid

• Buying just enough. A filter sized at the limit of its volume can clog faster. If you hesitate between two sizes, take the larger one, provided you can adjust the current.
• Forgetting the height. Check the height of the aquarium and the stand: an external filter pumps to a certain height, indicated on the sheet.
• Neglecting maintenance. A filter that is difficult to open ends up being cleaned too rarely. An accessible pre-filter saves time.
• Replacing the old filter all at once. It contains your bacteria. Run the old and the new together for at least six weeks, as advised by Swell.

Frequently asked questions

Which filter to choose for a 60-liter aquarium?

An internal filter is suitable for a lightly stocked 60-liter tank, for example a model designed up to 60 or 80 liters. If you want to free up the tank or plan a denser population, a small external filter offers more filtering volume.

Internal or external filter: which is best?

Neither is better in absolute terms. The internal filter is compact and economical. The external filter has more volume for filter media, requires less maintenance and frees up space in the tank, but costs more.

Which filter for a shrimp aquarium?

Choose a sponge filter or an air filter. The fine surface of the sponge prevents small animals from being sucked in.

Is a filter that is too powerful a problem?

It can be. A current that is too strong tires the fish that like calm water, such as the betta, and lays down the plants. Reduce the flow rate or diffuse the water outlet.

Should you turn off the filter at night?

No. The filter must run continuously: the bacteria attached to the filter media need a constant flow of water.

Read also

For flow rate: What filtration flow rate for an aquarium?

READ THE ARTICLE

Read also

For operation: Understanding the filtration mechanism in an aquarium

READ THE ARTICLE

Read also

For volume: How to calculate the volume of an aquarium?

READ THE ARTICLE

Last updated: November 4, 2026.