Pool Pumps — Everything You Need to Know 

 February 8, 2022

By  Tricia Hale

Pool maintenance is important to any swimming pool owner. Understanding the basics of how your pool pump system works is a priority because knowing what’s gone wrong and what to do will save you time and money in the long run. It also helps avoid issues with bad pool water, which can affect you and your family’s health.

The pool pump is what keeps a pool from turning into a stagnant, smelly mass of algae. Every pool needs one, as it is essential to filtering the water and keeping the pool clean. Water is pulled into the pump and through a filter that sends the cleaned water back into the pool where the water circulates. 

To clean a pool properly, a pump should filter all of the water in the pool at least twice a day. A stronger pump that filters faster than that is even better. A bigger pool requires a bigger and faster pump to keep up with the amount of water in it.

How Does a Swimming Pool Pump Work?

Swimming pool pumps are extremely important in keeping a pool clean and filtered. Movement of water is necessary in order for chlorine to be dispersed evenly through the water. It also keeps the water from becoming too stagnant and collecting bacteria.

Pool pumps are considered to be the heart of the filtration system for the pool. The filtration is performed mainly by the pump pushing water away from the center point of the pool using centrifugal force. 

Swimming pool pumps will always have a source for the water to go in, and then another source for the water to go out. 

All swimming pool pumps create high-speed water pressure through the use of an electric motor shaft that creates power for an object called an impeller. The impeller then begins to spin another object called a volute. 

The volute is what creates the velocity in the water, pushing it outwards. This outward momentum creates a vacuum that will expel air from the system. As the volute creates more energy, the velocity of the water changes. It is this constant change in velocity that allows the water to flow freely and constantly through the filtration system. 

The motor of the pump is what spins the impeller. It is the process of spinning the impeller that brings water into the pump before it is pushed out. The shaft of the motor spins and this spinning, in turn, spins the impeller. The impeller spinning sucks water into the pump before being filtered and pushed out the other side. 

Different motors will convert electricity into energy at different rates. The more efficient a motor is, the more power it can produce given a certain amount of electrical current. 

A swimming pool pump is vital to all swimming pools to keep the water healthy and safe to swim in. The more efficient the pump is, the more capable it is of pulling water in and pushing it out of the pump. Pumps do not necessarily need to be left running all the time, but they should be used at least a few times a week for best results.

What Are the Key Components of a Swimming Pool Pump?

Pool pumps are often described as the beating heart of any pool system. Just like a heart pumping blood, a pool pump pushes water and chemicals throughout the pool and filtration system. 

Another name for a pool pump is a centrifugal pump. Water comes through the inlet and is pushed out of the outlet using mechanically generated centrifugal force. 

The pump motor is usually an electrical pump, powering an impeller that spins a volute. This, in turn, pushes water out of the outlet at a high velocity. Displacement of water causes a vacuum inside the pump, which “sucks” more water into its place through the inlet. It’s important to note the pumps don’t suck in the traditional sense — if you examine pump operation, you find that they push water through the system. 

So, a pump can be summarized into three sections — an electrical motor, a mechanical drive section, and the hydraulic (water) section. Besides these, there are interdental parts such as the pool pump timer, pool pump cover, and display.

  • Impeller

The impeller of the pump is quite often considered the most important part of the swimming pool pump. This is the only part of the pump that actually is in motion during use. 

The impeller received power from the motor and spins. This spinning is what creates the high velocity of the water and allows it to enter and leave the pump. 

There are three different types of impellers; open-faced, which are used for sewage pumps, semi-open faced that are used in old pumps, and then closed-faced impellers that are much newer and are the most efficient versions as of right now. 

An impeller is the moving part of the pump — it rotates inside the pump and drives fluid by its rotation. It has curved fins that move water out of the way when it spins, creating a vacuum in their place that in turn draws water in its place, which is again moved out of the way when the fins push it. 

The main type of impeller you’ll find inside your pool pump is a closed face impeller — they’re much more energy efficient because they can pump more water for the same amount of input power. Older pool pumps may have semi-open face impellers. 

  • Pump Basket

Swimming pool pumps will also have a pump basket. The basket is there to filter out lots of different types of debris that could cause clogging and other damage to the pool. 

Things such as lint, hair, and leaves will all be caught in the basket as they are sucked into the pump. These baskets generally need to be cleaned once or twice a week to prevent buildup and keep the pump running efficiently. 

The pump basket collects objects that are drawn into the pump through the inlet. It’s usually accessible via the top of the pump. It collects stones, twigs, and anything else small enough to be drawn into the pump but could damage the impeller or block the pump. 

Cleaning the basket is vital; a permanently clogged basket leads to lower efficiency and shorter pump lifespan. 

  • Strainer

All swimming pool pumps will also have a strainer. In order for water to flow through the pump, there cannot be any air inside of it. A strainer is a ring seal that covers the pump housing to make sure no air gets inside. 

As the impeller spins inside the pump, water is added to the strainer. The water inside the pump is then thrown over the edge, and any air inside the pump is evacuated, thus creating the suction that pulls water into the pump in the first place. 

These strainers and seals also prevent water from leaking out of the pump at the motor shaft.

  • Pump Housing 

The pump housing is the metal casing around the pump to which piping connects. It’s important that the O-rings on the housing are intact and well sealed to prevent air being sucked into the pump. The only instance that air should be in the pump is when it’s started up, or “primed,” during first use. 

  • Pump Seal

Otherwise called the mechanical seal, this is a device used to stop leaks occurring at the motor shaft. Leaking water at the shaft is bad for the pump, so when the shaft driving the impeller spins it needs to do so without leaking. This is a part that’s commonly repaired or replaced in pool pumps. 

  • Pump Motor

The pump motor is the driving force behind your pool pump. It’s responsible for driving the impeller by spinning it. 

There are a wide variety of electric motors that can be used, some more energy efficient than others. Generally, the motor contains windings of wire that produce a magnetic field when AC electricity flows through them, which turns the rotor, which turns the shaft and impeller. 

The motor can be digitally controlled too, depending on the type of motor used, so a variable-speed pool pump is not only the most efficient option but also the most convenient. 

Installing a Pool Pump

Once you have found a pump with the proper flow rate to circulate the entire pool at least twice in a 24-hour period, it is time to set it up. 

Setting up the pump is the final step of the process but it is far from the least important. The location of the pump is important, it must be able to pump the water effectively, and therefore it cannot be too high or too low from the water level. 

Most above-ground pools have an outlet toward the bottom of the pool, which means setting an above-ground pool pump and filter combo at ground level works fine. 

It is also going to require either power so an extension cord or a nearby outlet will be required. It is important that the cord and outlet are located as far from the pool as possible so there is no risk of electrocution or stepping on the cord.

What Can I Do to Extend the Life of My Pool Pump?

Considering not only the cost but also complications involving replacing or installing a pool pump, getting the longest life out of this major investment is a worthwhile goal. 

Acting as a figurative heart, the pool or spa pump/motor/filter setup is critical for the circulation and filtration of the water as well as the even disbursement of the chemicals needed to maintain the appropriate levels of PH, chlorine/bromine, and overall cleanliness of the water. 

Through the force of the impeller being rotated by the motor, water is drawn in through the pool inlets, filtered, and then returned to the pool. This process also circulates the water so that it remains fresher and chlorine/bromine is distributed evenly. This of course keeps the levels of bacteria and other contaminants at acceptable levels for bather safety. 

  • Choose the Correct Pool Pump

One of the most important factors to the longevity of a pool pump is having the correct size of pump for your particular application. There are several pump/motor types available and your installer can assist with making an informed decision. 

While it is tempting and perhaps even practical to install a pump system that is larger than needed, many states, cities, and localities require certain energy efficiencies or pump types, which can limit your choices. 

A common question is “how long to run a pool pump,” but this will simply depend on your own use case scenario. We recommend running a variable-speed full-time as it will keep your pool clean and safe without significantly increasing electricity costs.

And as with most expenses in life, you get what you pay for in that investing in a good quality pump and filter system upfront may provide a longer, less troublesome life for the setup. It also pays to choose a variable-speed pool pump over a single-speed pool pump even if the initial price is higher.

  • Pool Pump Maintenance

Another major aspect for pump/system durability is maintenance. 

All pool pump systems will use at least one pre-filter screen, such as a skimmer basket, to catch larger debris such as leaves. These generally need to be cleaned at least daily. 

Downstream from the screen will be the actual filtration unit that may utilize sand or diatomaceous earth as a filter media to catch much smaller particles such as sand, hair, grit, or soil. 

An excess buildup of contaminants in the main filter can limit the ability of water to flow through it and thereby increasing the workload for the pump. Backwashing or replacing the filter media as prescribed will allow for less restrictive water flow making it easier for the pump motor to move the desired water flow, which also will contribute to a longer life for the system. 

One last item for maintenance is for those who may live in colder areas and will be using their pool seasonally. If the pool or spa is to be exposed to freezing temperatures the pump, filter, and associated plumbing MUST be drained. Water freezing within the pump housing, filter, or water lines may cause them to crack or break necessitating their replacement before being used again. 

So, do your research, get good advice and take care of your pump system and you should enjoy many years of trouble-free use.

  • Troubleshooting a Pool Pump 

Having a working and clean pool is a must-have on hot summer days, but the dreaded sound of a failing pump can ruin a great pool day. Without a working pump, your pool can’t circulate chemicals and filter the water, leading to a buildup of nasty bacteria, viruses, and water pollution. 

But don’t fret — when troubleshooting the pump there’s several common possible causes and solutions to consider before buying a pool pump replacement.

Remember! Pool pumps are heavy machinery and can be dangerous. Always disconnect your pump fully before you start working on it and be sure to follow any data sheet and manual advice. If in doubt, call a professional. 

  • Screeching, Clanging, and Clunking Noises

A dreaded sound that no pool owner wants to hear. It’s annoying and disturbing for you and neighbors. 

If the clunking noises are coming from the pump, it could be a lack of water flowing through the system. The first steps are to check the suction lines and make sure enough of them are open. Starving the pump of water will cause it to make too much noise as it fights to operate. 

You should also check the skimmers around your pool. Clogged skimmers will stop water being drawn into the pump. If your pool system is clean, it could be your pump is too big or powerful for your given pool and is starved of water. 

Screeching noises, perhaps the most annoying of all, can be caused by faulty or worn bearings inside the pump. These can be changed by a professional or by yourself with the right know-how. Many pool owners instead buy a new electric motor for the hydraulics section. 

  • Sucking Air and Poor Suction

Air entering the system is a big problem for pump performance. It’ll cause strain on the pump, which lowers the lifespan, and it won’t operate at full capability. 

Finding a leak can be hard because there’re many points at which it can happen. Check the pump (basket) lid is secured properly, as this is usually the cause for air getting into the pump. If that doesn’t help, check the inlet piping and connections for cracks and poor sealing. 

Check the pipe connection to theScreeching, Clanging, and Clunking Noises 

A dreaded sound that no pool owner wants to hear. It’s annoying and disturbing for you and neighbors. 

If the clunking noises are coming from the pump, it could be a lack of water flowing through the system. The first steps are to check the suction lines and make sure enough of them are open. Starving the pump of water will cause it to make too much noise as it fights to operate. 

You should also check the skimmers around your pool. Clogged skimmers will stop water being drawn into the pump. If your pool system is clean, it could be your pump is too big or powerful for your given pool and is starved of water. 

Screeching noises, perhaps the most annoying of all, can be caused by faulty or worn bearings inside the pump. These can be changed by a professional or by yourself with the right know-how. Many pool owners instead buy a new electric motor for the hydraulics section. 

 inlet, O-rings, gaskets, and any valves. It can be hard to see where the leaks are, so use your finger or shaving cream to feel or see where the leaks are. At the position of the leak, the shaving cream will be sucked in and leave a hole in the cream. 

Blockages can be an issue for poor suction, in which case you’d want to check all inlets and connections for debris. 

  • Leaking Water 

Leaking water is usually caused by leaking seals. If your pump has water underneath it, and it’s not from any piping connections, be sure to check the impeller O-ring and shaft seal looking for cracks and wearing. The shaft seal stops water going back towards the electric motor, so it’s especially good to check this. 

Some owners outright replace their pump at this point, but they can be repaired by installing new seals and O-rings. 

  • Humming Noise and not Starting

In this case, the humming noise is coming from the electric motor because it’s being prevented from turning. This can be because the impeller is jammed (the disk that spins inside the pump). Debris can be the cause of this, or sometimes just general wear. 

If you think this is the case, take off the impeller casing and remove any debris inside the pump. Be sure to turn off the power first though. 

  • Pump Basket Empty of Water

This is a common issue and means your pump needs priming or re-priming. This means evacuating air from the pump and letting the pump operate as designed. 

How to Prime a Pool Pump

The process priming the pump will vary depending on the pool pump.

1. First, turn the multiport valve to recirculate, making water flow through the multiport valve and back to the pool without flowing through the filter.

2. Remove the lid of your pool pump, and fill out the pump housing using a garden hose. Fill the pump housing for at least two minutes to ensure there is enough water for pump suction.

3. Replace the pump housing lid and switch on your filter system. 

If the pool pump priming has been successful, there will be no visible air bubbles in the lid when the pump housing starts filling up.

The key to priming your pump is to follow the steps exactly. Make sure you’re not drawing any water from the intake pipes to begin with, make sure you’ve manually filled the basket side and replaced the cap, and let the pump operate as designed until the water exits the relief valve on the outtake. 

Sometimes you will need to go through the steps multiple times to correctly prime the pump. 

If in doubt, always contact a professional mechanic or engineer to look over your pump. Problem-solving isn’t always an easy job, but sometimes it’s worth exhausting all possibilities before throwing out your pump and buying a new expensive one! 

Tricia Hale

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