How A Pool Pump Works

Written by:  Danny Rhodehamel
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This page provides a short tutorial on the main parts of a pool pump and how a pool pump works. This example describes a Hayward Super II Pump but the pool pump's parts and it's operation are common to most pool pumps.

Tips & Warnings

Video

Things You'll Need

Step by Step

Step 1
how a pool pump works

This picture shows the main parts of the pool pump in a pump cut-away. These parts include: the strainer basket cover that provides access to the strainer box to add water and clean out debris; the strainer basket that filters the larger pieces of the debris; the diffuser that direct water to and collects water from the impeller; the impeller that generates water pressure through centrifuge; and the motor that drives the impeller. Also shown are the two ports where water enters into the pool pump from the pool and exits out or the pump to return to the pool.

Step 2
pool pumps

This picture shows the basic flow of water through the pool pump. Water is sucked in through the basket, through the center of the diffuser (yellow) and through the center of the impeller. As the impeller spins, the water is thrown out the outer slots of the impeller where it is collected by the diffuser. The water is then funneled though slots in the diffuser into the high pressure water chamber and then out the exit port to the pool. Two notes: this picture shows a cut-away of the pool pump so that you can see the internal parts of the pump. In a working pump the diffuser would completely enclose the impeller. Also the only moving part in this pool pump is the impeller driven by the motor shaft. It's centrifugal motion is what sucks the water in and pushes the water out under pressure.

Step 3
how a pool pump works

This picture shows the inner operation of the diffuser with the diffuser partially pulled off. The diffuser funnels water from the strainer pot into the center of the impeller, then collects spun water from the outside edges of the impeller and releases the water through its own slots into the pressured chamber (dark blue arrows).

Step 4
pool pump impeller

This picture shows the operation of the impeller. Water enters the center of the impeller. As the impeller is spun by the motor, a series of blades, like a fan, push the water to the outside edges of the impeller where it exits through slots to be collected by the diffuser. It is this centrifugal force that generates the high pressure of the water exiting the pool pump.

Step 5
pool pump chambers

The pool pump has two chambers: chamber 1, the strainer pot, in the pull side of the pool pump before the impeller; chamber 2 is the push side of the pump after the impeller. There are four seals that keep the water flowing correctly between the chambers.

Step 6
how a pool pump works

This cut away of the pool pump shows the 4 seals that are part of most pool pumps: the strainer pot gasket, the diffuser gasket, the housing gasket, and the motor shaft seal. Their deterioration is the source of many of the common pool pump problems that plague pool owners.

Step 7

The strainer gasket usually sets in a groove on top of the strainer pot and provides a seal for the strainer pot cover. A poor strainer gasket will allow air to be sucked into the pump and prevent priming. The instructions for replacing a pump lid O-ring are included in the following guide: How To Clean Out the Pump Strainer.

Step 8
pool pump diffuser gasket

The diffuser gasket provides a seal between the strainer pot and the chamber around the diffuser and impeller. This chamber collects the pressurized water that is released through the output port. Without this seal the pressurized water will blow back into the strainer pot and the pool pump will loose pressure. For instructions in how to replace a diffuser gasket go to How To Replace Pool Pump Gaskets.

Step 9
how a pool pump works

The housing gasket provides the seal between the motor assembly and the pool pump assembly. If this seal is bad, the water will spray out of the pool pump and you will loose pressure and water. For instructions in how to replace a housing gasket go to How To Replace Pool Pump Gaskets.

Step 10

The motor shaft seal prevents water from leaking out of the pressure chamber along the motor shaft into the motor assembly. When this happens you will see water dripping from the bottom of the motor. For instructions in how to replace a motor shaft seal go to How To Replace A Motor Shaft Seal.

Step 11
how a pool pump works

If you are repairing your pump or pump motor consider purchasing a GO-KIT. Each GO-KIT contains the replacement seals and gaskets you will need to repair your pump. A typical GO-KIT like the one pictured here for a Hayward pump, contains the motor shaft seal (2 parts), the pump housing gasket, the pool pump lid o-ring and the diffuser gasket. Note: These GO-KIT are generally unique to the make and model of the pump. Order the GO-KIT specified for your pump's make and model.

Comments (1 to 40 of 99)

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User: Inyopools

uitfan21 - Check the voltage coming into your pump. If your pump is set up for 220V, you should have 220V supply. Check that all connection to the pump are tight. If you are using an extension cord, make sure it is heavy enough to carry the current to the pump. Then I would contact the company you bought the pump from. You may have a bad pump.

User: utfan21

Our pool pump is 2 weeks old and now will not work as of today. It will not come on or make any noise when plugged up. Any ideas what could be wrong? I checked all the breakers and nothing is tripped. There is power going to the pump it will not come on.

User: Inyopools

trixie0318 - Sounds like you are getting air into the system and the pump is not fully primed. Is the strainer basket full of water? Do you have any other suction ports open? You should not run the motor on and off like this. It will damage the motor.

User: trixie0318

Due to a large amount of algae we decided to drain our pool and Start fresh this year...got almost all of the water out of the pool and cut off motor..due to taking it was a couple of days later before we couple finish cleaning before we refill pool. There is about 6 in of water in my 24 ft round pool. We have vaccum hose hooked straight up to pump. Motor was working great then got hot started smoking and shut off...its on a safety switch. After few minutes pump will come back on after switch is reset but repeats. Housing is not staying full even with end of hose submerged. Is this due to water level or motor problems?

User: Inyopools

trav - Please click here for the Jacuzzi Magnum parts list. The picture shows two drain plugs at the bottom of the pump labeled "7". If this is where your pump is draining, these plugs need to be re-installed. They also have o-rings labeled "6" that are required behind the plugs. Make sure they are there. If the plugs and o-rings are in place and the pump is still leaking at these points, you may have to replace the o-rings.

User: trav

I have a jacuzzi magnum 1umf-s that pumps to a sheer descent. Whenever I open the valve to the pump, water starts draining from two holes near the bottom of the pump. How do I stop this?

User: Inyopools

judy - It's hard to pinpoint your problem based on your comments. Here's a link to our guide on "How To Correct Low Water Pressure in Your Pool System". It identifies some of the situations that cause low water pressure.

User: judy

I am so frustrated with my pool. I sure that you can help me.
My pool is 14 yrs old. My problem is the power in my jets. Either they are low or just stops. I have replaced the motor, gaskets, rings, caps & top of filter basket. After spending about $1,000, I have the same problem. This problem is intermitant so it's hard to fine. Because it works on & off, I keep getting algee & spending more money on products. Any suggestions for my pool man?

User: Inyopools

poolsss - This is a gravity fed pump so make sure it is installed below the surface of the water. Also if this pump has run for a period of time without water, you may have damaged the shaft seal, and, if so, it may be spraying water over into the motor. This could short out the windings and at this point you might have to buy another motor.

User: poolsss

This is our second year with an above ground pool and last summer, the pump worked fine, but this year when we put in the pump it first was leaking. We eventually got the leaking to stop but now the water is not being pump, entering or exiting. However, the pool pump is on and we can hear it. Now our water is green and we haven't been able to use it all summer.

User: Inyopools

Danny Slaughter - Polygroup had this comment in their literature. "When the pump is first started, there may be air present in the chamber that may create a vacuum and prevent water from going through the pump. Slowly open the air valve to release the trapped air and for the pump to fill with water then close the air valve. Your pump should be working fine now." If this doesn’t help, your motor should be covered by their warranty.

User: Danny Slaughter

I vaccumed my pool out yesterday. Afterwards, I proceeded to do as I always do and took the filter and skimmer basket out to clean it out then replaced it. After I went inside for a while I came back out and my pump had stopped working and we can't get it to work. We haven't even had it a month yet so will the manufacturer warranty cover a new one for it?? Please help bc I can't afford to buy a new one! Or if anyone can tell me what might be wrong with it and what parts I would need to get it fixed! I tried calling the polygroup customer service number today but they were closed and I need this fixed ASAP ??

User: Inyopools

reconnecting pool - Here's a link to common pool configurations: Plumbing Schematics. Also look at our guides on "How To Set Up In Ground Pool Equipment" and "How To Open Your Swimming Pool"

User: 

We jst bought a new homeand want toopen the pool. All of the connections are disconnected. Do you have anything that can showus how to connect? how to turn on etc?

User: Inyopools

Noisy motor - Take the motor out of the pump housing and check the state of the impeller and diffuser. Sometimes they are clogged or damaged by debris and the parts start rubbing against each other. If the parts are good and you have an older motor, the motor bearings may be going and it's probably time to get another motor. If you need to replace the motor, look into buying an energy efficient (EE) one.

User: 

my 1 hp hayward in grond pump works ok but seems to be noisey is something going.

User: Inyopools

poolma - Sounds like your problem may be in your filter. The backwash setting bypasses the filter. If your system has a good flow through the backwash setting and poor flow in the filter setting, try backwashing your filter a couple of more times. It may be time to replace your filter sand or DE. Also check to make sure that your motor's impeller is not clogged. If clogged it might provide enough pressure to backwash but not to filter. See our guide on How To Clean out a Pool Pump Impeller.

User: poolma

How do I locate the problem.
The pump works fine to back wash the system but when I switch it back to run(circulate)them water in and out of the pool is minimal. The motor sounds like it's run fine but isn't moving the water through. The skimmer baskets won't even stay in place. What do I do first? The temperature is rising please help!

User: Inyopools

Pat - Intermittent pump operation can be caused by the wrong or unstable voltage to your pump's motor. If the motor is set up to run on 220V and it is wired for 115V, it will become over heated and temporarily shut down to cool. This will damage the motor over a short period. Use a volt meter to check the voltage into your pump's motor. Also check that the voltage to the motor is stable and does not decrease more than 15% up and down. If it is unstable, contact your power company.

User: Pat

My pump will shut off for 30 to 45 seconds and then come back on and run fine for 30 minutes or so then shut off again. Its been doing this since it was new. It does'nt seen to hurt anything, what may cause this.

User: InyoPools

Jim - I would pull the motor off of the pump and check that the impeller is still sound. If the impeller is good, check for leaks on the suction side of the pump. See our guide on locating leaks. Otherwise, like you say, you've done well to have this motor for 14 years. It may be time to replace it with a more efficient one.

User: Jim

My pump motor is operating, but it is not pumping the water. It doesn't make any unusual noise. What is the most likely cause. Could it be that the impeller is has broken loose from the motor shaft? Is it likely that I need a whole new pump. The motor pump assembly is fourteen years old.

User: InyoPools

Richard - Check for obvious leaks around the filter or any joints you separated to change the sand. Check to see if water is going out your waste line. If it is, you may have a blown spider gasket in the multiport valve.

User: Richard

after changing the sand in my filter whenever i have the pool on filter the pool is losing water as if the waste outlet may be open? please help

User: InyoPools

Dennis - Take the motor out of the pump and see if you can spin the shaft easily. If not , you may need a new motor. Also check that the impeller is not jammed. Then check your motor's capacitor. It may have failed.

User: InyoPools

Francis - If you have a cartridge filter, you can bleed the air out by opening up the relief valve at the top until only water comes out. However I doubt that is your problem after running two hours. Sounds like you have an air leak. Check anything that was changed during the pool cleaning like the strainer basket. Is the cover gasket on correctly?

User: Dennis

Pump motor is not running at all. I have power from the breaker box, the breakers have been checked,they're fine the timer is fine and the time clock is fine have power to the pump but motor is not running Bad pump?

User: Francis

My weekly pool cleaners came this am, turned on the filter, cleaned the pool and then they shut the filter down. My pool filter starts at 10am, now two hours later the jets are spitting out air bubbles and water. The motor window has air in it. Question, how do I get the air out?

User: InyoPools

wet - You may have a bad capacitor. See our guide on checking and replacing a capacitor.

User: wet

All of the sudden my pool pump stops working, (its a Hayward , 3 years old) its emits a buzzing noise and the breaker (cut-off) jumps. It took it apart, a can turn the impeller using the shaft of a screwdriver, i feel some resistance.The impeller is clean of debris. is start the pump, its just buzzes and the breaker jumps again. My motor is shot?

User: InyoPools

concerned pool owner - I'm not sure what's going on here. You say you hear the water running but nothing's coming out of the returns to the spa or pool. Where is the water going? It has to be going somewhere if you still have good suction. Do you have a major leak and is your pool water level dropping?

User: concerned pool owner

My pool pump was circulating water through the filter and out to the inlets in the pool and fountain in the hot tub. It was running for awhile and realized later that I could hear the motor but no water was cascading out of the hot tub or comming out the inlets. When I check the filter to the [ump it had no debree but the water was super hot. I shut everything off check the valves and tried it agai i could here the water rush again no fountain no inlets when I turned on the sweaper line the sweaper took off however still no fountain nor inlets any suggestions would be appreciated..

User: InyoPools

pchickey1 – According to the manufacturer, the strainer pot assembly screws into the center of the housing assembly. If it isn’t holding, the threads in either the housing assembly or the strainer assembly may be stripped and either or both pieces may have to be replaced.

User: 

I can't get the strainer pot assembly to stay connected to pool pump. It keeps coming off. O-rings appear to be OK.

User: InyoPools

danny, I would check the impeller to see if it is clogged. If it is ok, you may have slow leak on the suction side of the pump or a partial blockage in one of your lines.

User: InyoPools

jr32016 - I would pull the motor out of the pump housing and check that the impeller is not broken or worn to the point that is rubbing on the diffuser around it. If the impeller is good and not wobbling on the shaft, it is likely that your motor bearings are going and it may be time for a new motor.

User: InyoPools

cheappool - I would replace the pump/filter set with a Game SandPro 50 Pool Filter System, model number 4510. Many customers are using this set to upgrade their Intex pools. Game even provides adapters to fit existing Intex piping as well as others.

User: danny

my water flow is about half what it use to be. is it possable that my impellar is clogged

User: jr32016

Suddenly my pump start making a loud noise seems to be working fine but with this loud noise is there some lubrication needed? or need to replace something

User: cheappool

I have a cheaper pool....collapsable, blow up top ring and fill pool....(probably less than $300) with a cheaper pump that was included. My pump will work, motor runs, but a very slow flow. Any suggestions?

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These guides are suggested use of your pool or spa equipment and may vary
depending on which product you are using.