Why does an aquarium pump make noise?

Identify the noise

The type of noise points directly to the cause. Take a few seconds to listen: is it gurgling, humming, or clicking?

To locate the source, turn off the aquarium equipment one by one (filter, air pump, heater, lighting) and note when the noise disappears. Sometimes a noise attributed to the pump actually comes from an air stone or a vibrating lid.

Cause no. 1: air in the pump

Gurgling or regular crackling often indicates air in the impeller chamber. It appears notably:

• after restarting, when air has remained trapped;
• when the water level has dropped due to evaporation and the pump is sucking in air;
• when the water outlet is positioned to suck in bubbles near the surface;
• when a hose connection lets air into an external filter.

This noise is not only annoying: a pump that regularly runs with air wears out faster, because water also serves to cool and lubricate the impeller.

Solution: top up the water level, tilt or gently shake the submerged pump to expel the air, and check the connections. On an external filter, use the purge or priming function provided by the manufacturer.

Cause no. 2: vibrations

A low hum that resonates in the cabinet or the glass almost always comes from transmitted vibrations. Over time, the suction cups harden, detach, and the pump ends up touching the glass or the decor directly.

• Check that the pump is not touching the glass, the floor, or a decor item.
• Replace hardened or deformed suction cups.
• For an external filter, place it on a soft support in the cabinet.
• Check that no hose is vibrating against the cabinet or the lid.

Cause no. 3: a dirty or worn impeller

The impeller is the moving part that circulates the water. It rotates around an axis, often made of ceramic. Limescale, mud, or biofilm deposits slow it down and cause clicking or squeaking. With wear, the axis or rings develop play and the noise becomes permanent.

For stubborn limescale deposits, use a cleaner dedicated to aquatic equipment like OASE PumpClean, on the part disassembled and out of the aquarium, then rinse thoroughly with clean water before reassembling. Handle the ceramic axis with care: it is fragile.

If the impeller has broken blades or if the axis is scratched or cracked, cleaning will not be enough: replace the part, or the pump if the part is no longer available.

Cause no. 4: a clogged filter or intake screen

When the foam or intake screen gets clogged, the pump struggles to suck in the water. It strains, becomes louder, and its flow rate drops. The noise then increases gradually over the weeks.

Solution: clean the intake screen and rinse the foam in aquarium water, never in hot tap water, to preserve the useful bacteria. Replace the foam when it deforms or no longer regains its shape.

Cause no. 5: the air pump

Air pumps (air stones) have their own noise, related to the vibrating membrane. It is accentuated when the pump is placed directly on a hard surface, such as a glass shelf or a hollow cabinet that acts as a sounding board.

• Place the air pump on a soft support or hang it.
• Check that the hose is not pinched and that the diffuser is not clogged: the pump would strain more.
• Install a check valve on the hose if the pump is placed lower than the water level.

Our article how to choose an air pump for an aquarium helps you if a replacement is necessary.

The case of external filters

External filters, installed in the cabinet, have their own noise sources. The closed cabinet can amplify the slightest hum, like a sounding board. A few points to check:

• Priming: after maintenance, air often remains trapped in the filter body. Use the provided purge function, and tilt the filter slightly to bring up the last bubbles.
• The seals: a dry or poorly placed lid seal can let air in and cause crackling. Clean it and lubricate it if the manual provides for it.
• The position of the filter: it must be placed flat, on a stable surface. A soft support under the filter limits the transmission of vibrations to the cabinet.
• The hoses: too long or forming loops, they trap air and slow down the flow. Shorten them and avoid tight bends.
• The height: each filter has a maximum head height. A filter placed too low compared to the outlet works at its limit and becomes louder.

If the noise appears just after maintenance, it is almost always air or a poorly repositioned seal. Take the time to reopen and check before considering a failure.

Prevent noise

Regular maintenance prevents most noises:

1. Monitor the water level and top up the evaporation before the pump sucks in air.
2. Clean the intake screen and foam as soon as the flow rate drops.
3. Disassemble the impeller during each major filter maintenance.
4. Check the suction cups and replace them as soon as they harden.
5. Keep a spare part for older models, whose parts are becoming difficult to find.

When to replace the pump?

If the noise persists after cleaning, repositioning, and checking the parts, or if the flow rate remains low despite a clean filter, the pump may be at the end of its life. It is also an opportunity to choose a model better suited to the volume of your aquarium. Our article where to put the pump of an aquarium helps you install it properly.

Frequently asked questions

Why does my aquarium pump gurgle?

Most often, air is trapped in the pump or the water level is too low. Top up the water, expel the air by gently tilting the pump, and check the connections.

How to reduce the vibrations of an aquarium pump?

Check that it is not touching the glass or the decor, replace the hardened suction cups, and place the external filters on a soft support.

How to clean the impeller of a pump?

Unplug the pump, remove the impeller and its axis, remove the deposits with a soft brush and a dedicated cleaner, rinse thoroughly, and reassemble.

Is a noisy pump broken?

Not necessarily. Most noises come from air, vibrations, or deposits. A noise that persists after maintenance can, however, indicate a worn part.

Can you use any product to descale the pump?

Use a cleaner dedicated to aquatic equipment, on the disassembled part and out of the aquarium, then rinse thoroughly with clean water.

My external filter makes noise after maintenance, what to do?

It is often trapped air or a poorly repositioned seal. Use the provided purge, tilt the filter slightly, and check the lid seal before considering a failure.

Read also

• Where to put the pump of an aquarium?
• How to choose an air pump for an aquarium?
• Where to place the air diffuser in the aquarium?