Pool pump surging is a common problem that many pool owners will encounter. The pool pump and filtration system fill and empty with water causing a pulsing or surging of water through the pump. The pump fills with water, catches prime, then loses prime and the water level falls before refilling and catching prime again. This process causes an annoying surging noise and causes the filter to not operate efficiently.
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Air Leaks Cause Pool Pump Surging
One of the main causes of pool pump surging is an air leak in the system. If you have a surging pool pump this is the first thing you need to check out.
A pool filtration system is a closed system under pressure. Any air leak, even a small one, will cause air to be sucked into the system. The air pocket will cause the water level to decrease and increase in a surging motion.
An air leak will always be in the plumbing before the pump. This is where the pump motor creates a vacuum to draw water from the pool to the pump. After the pump the water is under pressure. If there is a leak after the pump water will squirt out of the plumbing.
When air pockets form in your swimming pool filtration system the pump has to work harder to circulate water through the filter and into the pool. The system loses efficiency and operates with reduced performance resulting in less clean pool water.
These leaks most often occur in the pipe joiners where the pipe fits into a bend connector or three-way connector. There is a tiny leak in the join and the pump pressure sucks in air through the leaking joiner. Usually it’s caused by pipe joining glue failure or not enough glue was used when first installed.
A loose pump basket lid is another source of air leaking into the system. The pump basket lid is a clear plastic screw on lid that allows easy access to the pump basket. Sometimes the pump basket lid is not screwed up tight and air can be drawn through the screw mounting. Maybe the O-ring seal has failed and needs replacement.
Valves are another common area that can leak air into the system. If you have a leaky valve, replace the valve.
Test for Air Leaks
The simplest way to test for air leaks is to smear shaving cream over all pipe joins, valves, gaskets, etc. If there is an air leak you will see where the shave foam is sucked into the system.
Vacuuming the Pool
When vacuuming the pool you may have inadvertently introduced an air pocket when connecting the vacuum hose to the skimmer box plate or pipe. Before connecting up the vacuum hose hold it over an outlet jet with the pump running to expel air from the hose.
The vacuum hose may have a split or leak at the end where it is exposed to the air and is drawing air into the pump. If the hose has a leak it’s time to replace it.
Pump Valve in Wrong Position
An incorrectly positioned pump valve or multiport valve may allow air to be drawn into the plumbing from the drain. The valve may not be fully clicked into the position and the inside of the valve is leaking to another port. Always ensure your valve handle is correctly locked into position.
Multiport Valve Gasket Leak
A pump valve or multiport valve with a worn gasket seal may allow air into the system. Spray soapy water over the valve when the pump is running to check if soap suds are drawn into the valve. If there is a leak replace the gasket seal.
Low Pool Water Level Causes Pool Pump Surging
The pool water level determines how effectively the skimmer box cleans the surface of the pool. The pool water level only has to be slightly lower than normal for the skimmer flap to not open fully when the pump is running. Surface debris is not drawn into the skimmer box.
If the water level is too low the skimmer box will form a swirling vortex and partially empty of water when the pump is running. This will cause air to be drawn into the plumbing which is eventually trapped in the filter tank. Ensure the pool water level is at least midway up the skimmer flap.
Note: Never let the skimmer box run dry as this will damage your pump motor. Pool pumps must have water flowing through them to operate properly. Without water the pump will over-heat, damage the pump and even burn out.
To solve the problem, add more water to your pool.
Sticky Skimmer Flap Causes Pool Pump Surging
A pool skimmer is a plastic box fitting with a rectangular opening built into the side wall of the pool. The skimmer box has a weir flap that floats open and closed with the water level and pump suction. When the pump is off the weir flap floats to the closed position preventing trapped debris drifting back into the pool. When the pump is operating the weir flap is drawn open and pool water flows into the skimmer box.
Sometimes the skimmer weir flap becomes partially stuck due to debris causing the skimmer box to quickly empty of water when the pump is running. The pump draws air into the plumbing which ends up in the filter tank.
Check the skimmer flap and ensure it is clean and free of debris to operate correctly.
Plumbing Obstructions Cause Pool Pump Surging
A partially blocked plumbing pipe will cause pool pump surging.
Common reasons for blocked pipes are:
- Leaves and debris have become stuck in the pipe.
- A small foreign object, such as a plug, has fallen into the plumbing under the skimmer basket causing a partial blockage.
- A frog, toad or other small creature has got into the plumbing.
- Undissolved pool salt has accumulated in the pipe.
- Calcium scale build-up in the plumbing pipes
If you have a partially blocked pipe you will need to flush it clear of insert a pipe cleaner into the pipe.
How to Bleed Air from a Pool Filter
If you have air trapped in your filtration system you need to release it for the system to operate effectively.
When air is trapped in the filter it becomes compressed at the top of the filter tank. Check the reading on the filter pressure gauge. When the reading is high it indicates there is air trapped in the system. Open the air pressure relief valve to clear the build-up of air pressure in the filter. Close the relief valve when water shoots out of the valve. This indicates all the air has been released. Now the reading on the filter pressure gauge should be back in the normal operating range.
Please read How to Read the Filter Pressure Gauge
Conclusion
Stop your pool pump surging by finding where there is an air leak. The leak will be before the pump. Or maybe water is restricted into the filtration system by a partial blockage.
If you have any questions or would like to know more information, please leave a comment below and we will get back to you as soon as possible.