Swimming pool pumps are a standard feature in the operation of swimming pools, that allow you to pump water through a filter, circulate the water and keep the water clean.

But if you’re a new pool owner or replacing a swimming pool pump for the first time, the vast number of swimming pool pumps on offer can be a tad overwhelming.

No doubt you’re thinking:

“Why are there so many different swimming pool pumps on offer? Do I really need a swimming pool pump? How do I know what size swimming pool pump to buy?”

Fortunately, if you are feeling overwhelmed by the questions above, you don’t need to continue living this way.

By learning just a few simple elements about swimming pool pumps, you will be able to make a confident purchase decision that’s right for your pool.

In this guide, we will look at:

What is a swimming pool pump?
Do I need a swimming pool pump?
What are the key components of a swimming pool pump?
How does a swimming pool pump work?
What size swimming pool pump do I need?

What is a swimming pool pump?

A swimming pool pump is an essential device that is used for efficiently filtering a pool. The pump pulls the water from the pool, pushes it through a filter and then circulates the water around the pool, leaving you with clean and safe water to swim and bathe in.

Do I need a swimming pool pump?

Swimming pool pumps are essential devices for efficiently filtering a pool and leaving you with clean and safe water to swim in.

Traditionally, pools would be cleaned by hand - removing objects with a skimmer. Unfortunately, while this is an effective way to remove large debris like leaves, it’s not effective at removing fine debris such as dust, sand and dirt.

If you appreciate swimming in dirt free pool water then a swimming pool pump can efficiently remove the fine matter that settles at the bottom of the pool.

Swimming pool heating pumps also offer an efficient and effective way of heating a swimming pool. By using advanced technology to capture heat found in the outside air, the pump can transfer the heat into the swimming pool, making the water more comfortable and significantly extending the usage period of the pool.

What are the key components of a swimming pool pump?

In terms of a basic swimming pool pump, there are five key components that you should be aware of. These are:

Water Inlet
Water Outlet
Filter
Impeller
Motor

The area of operation for each component is listed on the swimming pool pump diagram below.

Water Inlet
This is the area in which the pool water enters the pump. The diameter of the water inlet will be one factor that dictates the maximum flow rate of your pump.

Water Outlet
This is the area in which the pool water exits the pump. Again, the diameter of the water outlet will be one factor that dictates the maximum flow rate of your pump.

Filter
The filter is a major component of a high quality pool pump that collects debris before it exits the pool pump and re-enters the pool water. Built from a high quality, erosion resistant plastic, pool pump filters can also be known as sand filters or strainer baskets.

Impeller
Probably the most important component of a pool pump, the impeller is a spinning component that propels the water out of the pump (think of an underwater airplane engine and you’re on the right track).

It works by pulling the water into the impeller face and then expelling the water back out to the pool through its slotted side.

Motor
Priming the pump for motion, the motor is the force behind the pump which turns the impeller, sucks the water into the pump and then back out of the pump.

image showing the different components of a swimming pool pump


How does a swimming pool pump work?

A pool pump is the heart of a swimming pool. The pump’s main task is to circulate water, ensuring treatment chemicals are dispersed and the water does not stagnate. It does this by pulling water in through an inlet, funneling water through a filter and then pumping the water back out into the pool.

Step 1 - The water enters the pump

The pump pulls in the water from either the top or the side inlet.

Step 2 - The water is filtered

The water is pulled through a filtration system. The system can successfully remove both large (rocks, leaves etc.) and small (dust, sand etc.) debris.

Step 3 - The water passes through a heat pump (optional)

The pump has a fan that draws in air from the outside. This air is then passed through an outer evaporator air coil before going on to heat the water.

Step 4 - The water exits the pump

The impeller system then pumps the water out of the pump at speed, circulating the water around the pool.

What size swimming pool pump do I need?

When trying to find the right size pump for your swimming pool, there is generally one specification that you should be aware of - flow rate.

Flow rate

Flow rate is the volume of liquid which passes through the pump per unit of time.

For swimming pool pumps, flow rate will range from 30L/PM (litres per minute) to over 5000L/PM.

To find the correct pump size for your swimming pool, you need to find the flow rate that corresponds with volume of water in your swimming pool.

To do this, follow the simple steps below.

Step 1: Multiply your pool’s volume in litres by two

(Swimming Pool Volume x 2)

This will give you the litres per day that the pump needs to circulate so that the water will turn over twice.

Step 2: Divide your new swimming pool volume by 1440

This will give you the number of litres per minute that the pump needs to circulate so that the water will turn over twice.

Step 3: Match the L/PM (litres per minute) with the correct swimming pool pump

When purchasing a swimming pool pump, your pump will have a ‘Maximum Flow Rate’ in the specifications tab. Make sure to match your L/PM (litres per minute) with the correct swimming pool pump.

If you found the above confusing, then take a look at the calculations for a pump below.

Look:

Step 1: Multiply your pool’s volume in litres by two

My pool is 25 metres in length, 10 metres in width and 1.5 metres in depth.

By doing the following calculation - 25m x 10m x 1.5m - I know that my total swimming pool volume is 375,000 litres.

I then times my new swimming pool volume by two - 375,000 x 2

This equals 750,000 litres.

Step 2: Divide your new swimming pool volume by 1440


There are 1440 minutes in one day.

To find out how many litres per minute the pump needs to circulate (so that the water will turn over twice) I do the following calculation:

750,000 ÷ 1440

This equals 520

Step 3: Match the L/PM (litres per minute) with the correct swimming pool pump

My flow rate is 520L/PM

This means that I need to buy a swimming pool pump with a max flow rate above 520.

What swimming pool pump should I buy?

If you are in the market for a swimming pool pump then have a look at the options below. Each of these pumps have been tested by our in-house engineers and are the highest quality pumps available on the market.

Calpeda NMPM Pool Pumps 240

Crafted out of the finest cast iron with a compact, built-in strainer, the Calpeda NMPM swimming pool pumps are close-coupled, self-priming centrifugal pumps.

Suitable for:

- Clean or slightly dirty water
- Both commercial and domestic systems

Search prices on Calpeda NMPM Pool Pumps here.

Calpeda MPC Pool Pumps 450

Crafted from a mixture of cast iron and erosion resistant plastic, the Calpeda MPC Compact is a self-priming swimming pool pump with a built-in filtration system.

Suitable for:

- Clean or slightly dirty water
- Domestic applications only

Search prices on Calpeda MPC Pool Pumps here.

Calpeda Spa Pool Pump

Built from corrosion-proof plastic, stainless steel and cast iron, the Calpeda Spa pool pump is a self-draining, single impeller system that offers an impeccable range of pumping solutions.

Suitable for:

- Spas
- Hydromassage bathtubs
- Whirlpool baths
- Domestic applications only

Search prices on Calpeda Spa Pool Pumps here.