Why does my pond pump keep stopping?

Check that it is plugged in and switched on. If it is, go to the fusebox and check that your outdoor electricals circuit is switched on and hasn’t tripped. Next check the filter. Is the filter clogged up with dirt and algae, blocking the pump? If it is clean the filter and replace sponges if necessary. 

Check the sponge 

What type of pump is it? Does it have a prefilter sponge inside the pump itself? Switch the power off, lift the pump out of the water and inspect. Remove the prefilter cage if there is one and see if there is a sponge inside. Clean or replace that sponge if necessary.

Check the cage

Look at the outside of the pump cage and see if it is covered in algae, leaves and debris? If any of the inlet holes are blocked on thew pump cage remove dirt by hand, use a stiff brush, a hosepipe, or a jet washer, and make sure all the holes are clean and unblocked to allow the flow of water through. 

Open the pump cage

Find the clip or screws and open up the pump cage to reveal the pump inside. Check the holes inside the cage and clean if necessary. Inspect the pump inlet. If there is algae, leaves or snail shells they will block the pump for sure and stop it from working. Pull any debris out of the pump inlet using tweezers or a cocktail stick. 

Clean the impeller

Checking once more that power to the pump is turned off, open the pump impeller chamber, This usually involves twisting the bottom half to release it from its bayonet style fitting, but some are also held in with screws. Inside there should be the impeller, the circular or propellor shaped part that spins and pumps the water. Check that the impeller is completely clean of algae and debris and clean if necessary with an old toothbrush. 

All impellors are held in by magnets and can be removed. Pull the impeller out and inspect it. The cylindrical magnet should be clean and undamaged. If the impeller is cracked or warped, looks burnt or is stuck fast you may need a new impeller or even a new pump. Most impellers spin on an impeller shaft (a thin central stick,) so check that the shaft is one piece. If it’s broken you will need a new impeller shaft. 

Check the cable

If the cable is damaged or cut in any way you must throw the whole pump away and not use it. Buy a new pump.

Reassemble all the steps above, plug-in, switch on, and the pump should be fine again. 99 times out of 100 a pond pump stops because the pump or the filter is blocked. 

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Jeremy Gay is an author and freelance aquatic specialist. A former editor of Practical Fishkeeping magazine, he offers a wealth of experience on all things aquarium and pond.

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