The short answer
A noisy filter almost always comes down to one of three things: trapped air, grit or wear in the impeller, or a low water level letting the outlet splash. Work through those and most filters go near-silent. Rattles and hums are rarely a fault — they’re usually air or maintenance, not a dying motor.
The common causes
- Trapped air. A gurgling or bubbling sound means air is caught in the pump or hoses. Gently rock a canister to burp it out, or tilt an internal filter to release the bubble.
- Low water level. If the outlet or spray bar sits above the surface it splashes. Top the tank up, or lower the outlet just beneath the water line.
- Dirty or worn impeller. A rattle or grinding usually means grit, hair or debris on the impeller, or a worn shaft. Unplug, open the pump head, and clean it.
- Vibration against glass. A humming filter buzzing against the tank or cabinet transmits sound. Add a little foam padding or reseat it.
The impeller check
If cleaning the media and burping air don’t help, the impeller is the prime suspect. Unplug the filter, remove the pump head, slide out the impeller and clear any debris. Check the little magnet and shaft for wear or cracks — a worn impeller is a cheap, common replacement part.
For a deeper dive on noise specifically, see why is my aquarium filter so loud. Routine cleaning prevents most noise — read how to clean an aquarium filter and how often should I clean my aquarium filter. Browse the aquarium filters hub for gear.