Pond Pump Running But Not Pumping Water – Causes, How To fix

Clear water forcefully flowing from a blue pipe, depicting a functioning water pump.

The pump is the “heart” of your backyard pond. It is responsible for creating the pressure that moves pond water, thereby providing fresh, oxygenated water to the plants and fish.

Therefore, when your pond fish food pump stops pumping water, the fish, plants, and bacteria in the biological filter are at risk.

As with any mechanical equipment, your pump requires proper care and maintenance to function efficiently. However, it’s not uncommon for pond pumps to stop working as they should even after maintenance service.

How can you detect possible issues and hopefully fix them before contacting the installer?

Learning how to take care of your pond pump and even troubleshoot pump problems will save you time and money.

You can hear your pond pump running, yet it’s not pumping water. What could be the issue?

Your pond pump is a piece of mechanical equipment like any other and isn’t immune to problems. However, you’ll realize that the problems and issues that pond owners experience with pond pumps are relatively predictable and can be fixed.

If your pond pump is running, but you can’t see the water moving, be sure to check for the following possible causes and fixes before contacting the manufacturer.

Possible Cause: There Is No Enough Water In Your Pond

One of the most common pump problems pond owners often experience is non-existent or diminished flow rate.

Remember, your pump can only push water if it has access to it. You, therefore want to check to see if there’s enough water in the pond. Low water levels in the pond can cause your pump to operate intermittently or pull in the air instead of water.

How To Fix:

The water in your pond will evaporate during the hot summer months. This is a natural process.

You must, therefore, establish the proper water level in your pond for the pump to function and work efficiently. Make sure your pump has a continual water source.

Possible Cause: Is the Pump Vapor Locked?

The second possible issue could be that your pump is vapor-locked.

A vapor lock happens when the pond water is being sucked by the pump changes to vapor due to reduced pressure. The vapor gets trapped in the impeller chamber, locking the water and reaching the suction nozzle leading to a loss in the Net Positive Suction Head (NPSH).

As a result, the Net Positive Suction Head (NPSH) becomes higher than the pressure at the pump’s suction nozzle. Even though the impeller will keep spinning, it won’t be able to create the required pressure to move the water.

How To Fix:

The vapor generated is trapped in the volute.

You can fix this problem by tilting the pump underwater to let the air bubble escape through the inlet or outlet and allow for an upward intake of water.

Removing the pump from your pond and re-installing it can also help fix it.

Possible Cause: Pond Pump Blockage

If there’s a diminished or non-existent flow rate, yet the pump is running, your pump inlet or outlet could be obstructed.

An ill-placed twig or debris can affect your pump’s ability to push water effectively.

Water pumps are designed in such a way that they can handle small particles of debris. However, these particles will accumulate and build up over time, thereby affecting the parts inside the pump.

How To Fix:

Check to see if there’s any obstruction on the skimmer or intake. Check your pump filters as well. Clogged filters will starve your pump of water.

If you can’t find any debris or obstruction in your pump’s pre-filter or skimmer, consider unplugging the pump before you can check for debris inside the pump from the outside of the pond.

You should also check the tubing for any kinks.

Once you’ve removed the debris from the inside of your pump, check if there’s any damage to the O-rings. Note that the O-rings are one of the most critical parts, as they are responsible for sealing the pump.

When damaged, they allow debris to get inside the pond pump. You can easily replace them and get your pump working correctly again.

Possible Cause: Damaged Impeller

When tiny particles build up inside your pump, they can damage or even break the impeller.

Your impeller requires regular maintenance and cleaning to work properly. Blockages often cause impellers not to spin, so you should make sure there’s no debris inside your pump.

A worn-out or damaged impeller won’t pump water at full capacity. The fins on your impeller should turn 1800 before they lock. If your impeller can spin through a full 3600 without stopping, you’re dealing with a worn-out impeller than needs to be replaced.

How To Fix:

First, start by unplugging and removing the pump from the pond.

Follow your manufacturer’s maintenance guide to check for any debris blocking the impeller. Remove any particles, sticks, and rocks lodged and trapped around the impeller.

Firstly, if your impeller isn’t rotating at all, try to spin it using a pen or screwdriver manually.

Secondly, if it has not been in use for an extended period, likely, it won’t manually spin, in which case it will need to be replaced.

Water pump machinery connected to blue pipes, positioned near a pond, intended for water circulation.

Possible Cause: No Electricity

As with any other electrical device, pond pumps need adequate electricity to run smoothly. A pond pump with worn out breaker or faulty ground will stop working. This can be huge problem especially when you are not sure what is making the pond pump stop and can result in it getting damaged by a short circuit and not working at all.

How To Fix:

You may want to check the circuit breaker to make sure it is working normally and it not tripped. If that is not the case, you can even try plugging in another device to check if the power the reaching the outlet. You can also check the pond pump wires to make sure they are not damaged by wear and tear.

If none of this works, you may reach out to a professional electrician to troubleshoot the problem.


Pond pumps are essential to a clean and healthy backyard pond.

With a pond pump, the relaxing and peaceful sound of the water flowing over the rocks and the beautiful scenery wouldn’t exist. When it stops pumping water, you may have a couple of hours to avoid a catastrophe.

When a pond pump stops pumping water, there are a few things you can do to fix the problem.

The possible causes and fixes highlighted above are relevant to general maintenance and check that pond owners should follow regularly, especially when faced with this specific problem.

You must read and follow your manufacturer’s maintenance guidelines and user manual.

If you’re unable to identify or determine the cause of your pond pump problem, be sure to contact a pump repair professional or the manufacturer immediately.

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