How to troubleshoot a faulty airpump

Airpumps provide vital oxygen to ponds and aquariums, helping to keep fish and even filter bacteria alive. But lots of things can negatively affect airpump performance and the number of bubbles they produce, and sometimes air flow can stop altogether. 

Check for kinks

The most common cause of reduced or lack of airflow is a kink in the airline. Check the whole length of the airline to make sure it isn’t bent, squeezed or folded anywhere. If you need to bend airline through 90 degrees consider using a 90-degree elbow fitting. Silicone airline may also bend more easily without kinking versus PVC. 

Check the depth

If you move an airstone to a deeper part of a pond the water pressure will cause fewer bubbles to be released. Move the airstone to shallower water to see if the flow is restored, or upgrade to a larger, more powerful air pump.

Check the airstone

Old airstones can block and prevent air from flowing properly through them. Try a new airstone to see if the flow is improved.

Check the valves

Some airpumps have air control wheels built-in. Or a tap, valve or manifold may be fitted in the air tubing. Pull the airline off one end, turn the taps or valves to fully open and see if you can feel the air being blown from it. Remove the airstone and place the airline into a bucket of water. If bubbles are coming out the pump is working.

Turn the taps or controllers to see if the amount of air increases or decreases. Inline taps and valves can be removed altogether if you want maximum, unrestricted airflow. 

Check the non-return valve

More commonly fitted to aquarium airpumps, Non-return valves prevent water back syphoning in the event of a power cut. If water travels down the airline from the aquarium up above, the pump may be irreparably damaged and it may even cause a flood in your living room. 

Non-return valves do place a large restriction on the amount of air that a pump delivers, and if fitted the wrong way they block airflow entirely. 

Disconnect the non-return valve and look for a directional arrow moulded into its plastic casing. Blow down valve to see which way it allows air to flow, and then fit in inline in the air tubing.

Check the air inlet

All airpumps suck atmospheric air into the pump body before pushing it out at pressure via the outlet(s). Lift up the pump and look underneath to locate the air inlet. If there is a felt pad it may need cleaning or replacing. Check that the inlet isn’t obstructed when the airpump is placed back down. This can shorten the lifespan of an air pump. 

Spare rubber diaphragms are available for some airpumps

Service the pump

This isn’t for every fishkeeper, but airpumps can be opened up and serviced. Disconnect from the power supply first and then use a screwdriver to remove the screws in the pump body and lift off the pump’s outer casing. 

Inside is a rubber diaphragm on a metal arm. Twin outlet pumps will have two diaphragms and two arms. Check the diaphragm for signs of wear and tear, and damage. Depending on make and model, spare diaphragms and service kits may be available for pond airpumps, but for aquarium pumps its quicker and easier to replace the whole pump.   

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Jeremy Gay is an author, lifelong fishkeeper, and aquatic specialist. He's a former editor of Practical Fishkeeping Magazine, UK editor at Reefbuilders, a former aquatic store manager, and has collected fish in Sri Lanka and the Amazon. He's been on tv and radio, contributed to Koi Carp and Gardeners World magazines, been a product tester, a judge, and a product developer. Jeremy is here to guide and advise you on all things tropical, pond and marine, from set-up to stocking, health, feeding to breeding, as well as solving many common fishkeeping problems along the way.

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