Today, we tackle an issue that has plagued pool owners for millennia – what to do when the pool pump is surging, or pulsing. That is, when the water flows into the pump intermittently, it starts to catch prime, and then loses it, and then catches again. Surging pool pumps also make a tell-tale noise as the water level in the pump rises and falls. What is it that causes pump surge? Read on…
Air Leaks
Yes, the number one cause of water surging in the pump is a classic air leak. As the pump builds in water flow, the vacuum created increases, which makes it easier for small air leaks to become big air leaks.
What do I mean by air leaks? This is a void, in front of the pump impeller (Before the impeller), that is drawing air into the system when the pump is running. Your pump will prefer to pump air, rather than water – it is the path of least resistance.
The most common sources of air leaks? A loose and heat-shrunken MTA fitting coming into the pump is number one. A loose pump lid is second, followed by a damaged or dry pump lid o-ring without lube. Third on the list is a leaky suction-side valve; skimmer or main drain valve, or check valve.
You can test for air leaks by smearing shaving cream (yes!) over everything and looking for where it gets sucked in, or by using a Drain King to pressurize the suction-side manifold. The air leak will always be before the pump impeller, because after the pump, any void will leak water not air, as it is under pressure not vacuum.
Pipe Obstruction
Another cause of pool pump surging is when a suction pipe (skimmer, main drain or vacuum) is clogged, or partially clogged, I should say.
In some cases, it will be a clog of leaves or gum tree spiky balls, or acorns – and you may know this if you were just vacuuming heavy debris, and lost suction suddenly.
In other cases, it will be a too-small winterization plug that slipped down the pipe, or a piece of plastic. In both cases, the foreign object usually gets stuck at the first 90 fitting, directly below the skimmer, and the suction causes it to alternately completely block and partially block, the water flow, creating the pulsing pump.
A Drain King, available at your local hardware store and attached to a garden hose, can be inserted into the front of the pump (facing the pool), and used to push clogs backwards, toward the skimmer, where the material or object can be removed.
Low Water Level
Is the water level in the pool up to mid-tile? Even so, do you notice a swirling vortex in the skimmer, which is drawing air into the pump? This will cause intermittent flow problems, with the pump running fine until the vortex draws in a good stream of water, and then bogs down.
This is an easy problem to solve, just add water!
Stuck Skimmer Weir
The skimmer weir is the flap inside the skimmer throat. In some cases, when a skimmer’s side walls have bowed inward, this can cause the weir to become stuck in a vertical position, blocking water flow.
Discovering this one can be tricky, because sometime you go to inspect the skimmer and it has fallen back down to a normal, more horizontal position, mocking your attempts at solving the pool pump pulse problem.
You can manually test for the problem however, by removing the skimmer lid and reaching in toward the pool (easier with the pump off), and pushing the weir to a vertical position, and seeing if it will stay stuck.
Loose Pump Switch
A related problem, often accompanied by a clicking sound, is when one of the switches in the rear of the motor is chattering, or switching on/off, on/off…
In AO Smith style motors, there is a centrifugal switch on the end of the motor shaft, that can be loose, and not fully engage, or lay flat. Tighten the center screw and check that it is aligned with the tab on the triangular shaped stationary switch.
The stationary switch can also cause this problem of cycling on/off, on/off. This switch is located at 6 o’clock, and the screw at the bottom can come loose, or the tab can become misaligned with the centrifugal switch.
Century motors have a ‘switchless’ motor, which does have a switch on the end of the shaft, which can become damaged, or obstructed, so that it does not fully open.
Hi, question for ya….pool pump surging, water level ok, pump lid gasket replaced, and “spackled” around pipe fitting to pump basket. Continues to surge w/low pressure; yet next day runs normal. Been doing this last two weeks, running normal then surging next day(s). Not sure why some days n not other days. Any ideas?
TIA
Hi Nancy, could be that the water level is at such a point where a vortex of air is being drawn into the skimmer? Or, perhaps your skimmer weir is getting stuck in an up position, and blocking water flow into the skimmer, or a floating pool noodle perhaps? If the valve settings have been changed at all, like the main drain closed more, some restriction in the suction pipes can cause the pump to pull harder, opening air leaks that don’t appear when all valves are open. I would also still be suspicious of the intake pipe, sometimes a putty fix can continue to leak, or one of your incoming suction valves may be leaking air around the valve stem, under the handle. If you buy a Drain King at the hardware store, and attach to hose and stick into the skimmer, and close the main drain, and plug the pump intake, or put the multiport valve on closed, and turn on the hose on low, (with pump off), you may find the leak, something dripping, before the impeller, under pressure, which would be an air leak when under vacuum.
Hello, we have a Hayward superpump 1.5hp for our concrete inground pool. It has brand new sand and filter parts as well as new piping from the filter to pump and filter to pool. The pump o-ring and lid has been replaced and lubed. It all of a sudden started surging from 0-10 after working for about a month This happened after vaccuming some junk from the deep end. We have checked all the lines for air leaks and there are none. All of the baskets are clear as well as the impeller. We have tried on both basket ends to flush out or vaccume out the lines and nothing but water comes out no clutter or gunk. We’ve used both a shop vac and a plumbing tool to do so. We are at a loss now and aren’t sure if the pump itself is going bad. It’s not making any crazy noises just surging.
HI Caitlin, ok I understand. First thing is to check around the pump lid. Be sure that the pump lid is tightening down all the way, and the new gasket has ridges side up. Did you buy a Drain King? If you put the drain king in the skimmer with the garden hose, turn the hose on (low) and close the filter valve, you should see any air leaks start dripping, specifically around the pump lid, front drain plug or the pipe that threads into the pump. Or it might be a leaky skimmer or main drain valve. You can also use the Drain King the other way, to unclog skimmer clogs, which can be difficult, but try this method: put the Drain King at the pump, facing the pool, turn garden hose on high, and close main drain valve very tightly. Use a plug at the skimmer hole, or a tennis ball and hold over the skimmer hole tightly for 3 seconds, release for 1 second, repeat, repeat, repeat… it’s a ‘water hammer’ technique, to help unclog skimmer clogs.
In my case, there was a glob of big leaves and twigs in a ball that made it’s way to the Jandy Space Saver valve and blocked most of the inlet to the pump basket. Four screws, clean it all out and boom – problem solved – after I checked everywhere for air leaks, of course. Thanks.
My jacuzzi magnum pump is humming when I try to start it. I check the breakers and they look good. I noticed a couple weeks prior the water motion was smooth when I ran the cycle and it would change to a vigorous motion back to smooth. This is an old pump but has been great over the years. Does sound like the motor is gone? Should I replace or repair?
Hi Gia, the surging you experienced may not be related to the humming problem now. When a pump hums and fails to start, it can often be a bad start capacitor, which is a black cylinder in the rear of the motor, that helps bring the motor up to speed quickly. It can also be that the switches (centrifugal and stationary) in the rear of the motor are not aligned. It could also be a loose wire or crimped wire between switches and capacitor, or possibly a loose power wire on the terminal board (where the incoming power wires connect). It may be worth trying a new capacitor, you may be able to get one locally, at an “electric motor repair shop”, replacing with the same exact MFD number, printed on the cylinder.
We have a waterfall next to our in-ground pool and following a power outage, the circuit tripped and if I reset it and try to turn the pump on, it hums a moment and then re-trips the circuit and won’t do anything. It kept trying to restart itself, leading to a momentary power surge in the house, and then would stop in a moment. Is this a surge issue, or could the circuit breaker simply need replacing, or something worse with the pump. Everything was fine until the outage.
It probably blew out the pump motor capacitor. The black cylinder at 9 oclock in the rear of the motor, the battery for starting the motor. Check that the motor shaft will spin freely, and that other switches in the motor rear look solid and tight.
Hello, we have a 18’ x 33’ Vogue Legend 8 bought in 2004. We have had several J hook/Unibead liners. I am curious to know if we can use an overlap liner this time as they seem to be less expensive. Can you give your thoughts, suggestions and tips? Thank you
You can use overlap, as long as you don’t have the liner track around the top of the pool wall, and there is nothing obstructing getting a liner to “lap over” the wall fully. If you have been using a J-hook, and ‘hung’ the liner on the wall, then an overlap could also be used. You would need to buy Coping Strips however, which are 2 ft long plastic U shaped clips that slip over the liner and top of the wall, to help clamp the liner over the wall.
We are trying to repaint the pool. We used acid wash, bleach and TSP. We are now ready to prime but have a problem. I have the hydrostatic valve open because we have a high water table and I assume there is a lot of pressure under there. Therefore, I can’t keep the deep end dry enough to paint because the valve is open. I’m worried about popping my pool. Will it hurt for me to close the valve long enough to dry it out and paint? What would you recommend?
Hi Jane, water has been coming into the pool, but slowly I assume? filling up just an inch or so…? If it doesn’t seem like there is a huge amount of pressure, I might do that, seal it up for 7 (dry) days, and cross my fingers. Make sure your homeowners insurance is up to date. 🙂 But check the weather, because heavy rain storms could be big problem! But if it stays dry, I’d go for it!
I have an inground pool. A few years ago the light burst. It apparently burned through the Nest and was “unrepairable.” We purchased a new liner and was told a light was not an option. He put covered the hole and installed liner over area. There are no cuts in the liner. I really would like to have a light in the pool. I have been told it is impossible, I would need a new liner, or I would have to break up concrete decking and replace the entire pool wall. Is this true? Is there not a way that the a new Light system can be installed? I am fine with cracking the concrete if necessary, but would I still need a new wall and new liner? Can a new Niche not be installed?
Hi Shannon, yes absolutely a new niche can be installed, you just have to expose the pool wall, cut a hole through the wall, and then run the conduit to a junction box, off of the pool deck, and then run conduit from the j-box to the breaker box. It may also be possible that the existing niche can be re-used, it would be very odd that something can destroy a niche and make it unusable, except for very old pools, over 50 years old usually. In recent years, new lights have come out that require a standard 1.5″ wall fitting, and are thus much easier to place and install. It would still require excavation and a lot of work, and because they are smaller lights, you would want two or three, instead of the one large light, but another possibility for you. They are sometimes called Nicheless lights, made by Savi, or Hayward Colorlogic, or Pentair Globrite.
Hi, I bought a summer waves 10×30 pool and by mistake turned on the filter for a couple of hours until I realized that I didn’t remove the drain plug. And now the pump is not pumping water. Could it be that the filter burnt out?
Claudia, possibly the pump has burnt out. Be sure that the water is entering the pump, and if it won’t move water, then perhaps the impeller has melted somewhat, or it could be that the hose connected to the pump is loose or shrunken from the heat. Check that the hoses are not collapsing from the suction as well…
Thank you for your reply. The water enters the pump and fills up the gasket. However, on the other end of the hose where it should blow the water back into the pool isn’t happening. And when the pump is on I can still hear the motor running but really softly.
Try removing the filter, sealing the filter back up again, and turning the pump back on, to see if water flows. If not, shut off, and disconnect suction hose (you may need to plug pool or close valve if you have one, to keep water from flooding, and inspect the pump impeller, which may be clogged with debris.
We have a Polaris 360 pressure cleaner that emits a white cloud where the return pressure line connects to the wall. When the pressure cleaner is not running the pool is crystal clear where the water is returning to the pool.
sounds like air? You can reduce pressure to the cleaner, or close the bleeder vent (at the wall) to prevent this.