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When Is the Best Time To Run Your Pool Pump?

Running a pool pump during the wrong time of day can lead to algae growth, frozen plumbing, and many other unwanted problems. Your pump needs to run at different times of the day during each season. However, some pool pumps are more versatile than others.

The best time to run your pool pump is during the warmest hours of the day when your pool has the most direct sunlight. Run your pump for one hour per ten degrees Fahrenheit. If your pool gets cold enough to freeze, run the pump at its lowest speed during the coldest hours of the night.

Throughout this post, I’ll explain the best time of day to run your pool pump, how many hours it needs to be on, and whether or not you can leave it off for extended periods of time.

What Is the Best Time of Day to Run Your Pool Filter?

The best time to run your pool filter is whenever it’s at its hottest. Your pool filter requires a pump for filtration. Your pump should run whenever there’s a high chance of algae growth. You could also run the pump around the clock when you’re getting rid of an algae bloom.

Ideally, you’d run your pump at a slow speed without stopping. However, this tip only works if you have a VSP. It’s also a bit expensive and can put unwanted wear and tear on the motor. Open the diverter valve to let all of the water flow through the filter. You should run the pump regardless of the clarity or the algae level.

I often recommend people run their pump between 11 AM to 8 PM during the summer. It’s enough time to prevent algae without going overboard. You can reduce the hours to 12 PM to 5 PM during the fall, spring, and winter. I’ll discuss a couple of exceptions below.

Is It Better To Run A Pool Pump At Night Or Day?

It’s better to run a pool pump during the day because algae grows when it’s warm outside. However, you should run your pump at night if the water might freeze. Frozen water can crack the plumbing and damage the equipment. However, the pump should always run when it’s warm during the spring and summer.

Running your pump at night can prevent freezing. Frozen pool water destroys the equipment. While it’s great for reducing algae, it’ll warp the plumbing. If you have a variable-speed pump, you can trickle the water at night and run it at a higher speed during the day. This issue usually only occurs during the winter and early spring.

How Many Hours A Day Should You Run A Pool Pump?

You should run a pool pump for one hour per ten degrees outside. If it’s 100 degrees Fahrenheit, you should run the pump for 10 hours.

The only exception to this rule is if you have a variable-speed pump and want to run it for more hours at a slower speed. You can also run a pump more often when it’s freezing to prevent the pipes from cracking.

All pool pumps have unique speeds. However, two-speed and variable-speed pumps let you control how fast they go. Faster pumps typically cost more money.

Variable-speed pumps can run at a slow speed throughout the day to reduce their energy consumption. The rare earth magnets keep them quiet without reducing their power output.

Here’s a list of five scenarios when you should change how many hours you run the pump:

  1. If you’re getting rid of an algae bloom
  2. When the water is freezing for several hours a day
  3. If you have a pool party and want to sanitize the water
  4. During rainy, windy days when there are a lot of phosphates in the pool
  5. When you use a water clarifier and want to remove the cloudiness from the water

Is It Cheaper To Run Your Pool Pump At Night?

It’s cheaper to run your pool pump at night because it has a smaller chance of overheating. Many utility providers offer lower rates during off-hours, which means your pump will be less expensive at night. However, you might have to deal with more algae blooms if your pool is hot and stagnant. This difference could cost you more in the long run.

While it’s cheaper to run the pump at night, it’s not always the best option. Below, I’ll break down why you should consider running your pump during the day, even though it’s more expensive.

  • Algae will grow in the warm pool, causing you to spend more money to get rid of it. I always suggest people run their pool when it’s at its hottest. Algae love warm, stagnant water. If you don’t have circulating water with chlorine, your pool will inevitably develop tons of algae.
  • Warm, stagnant water evaporates, so the pump needs to run to prevent it. Failure to run your pump at the right time will make your pool lose a ton of water. You’ll have to fill it with hose water, which will dilute the chemicals. Furthermore, you might spend more money on water than you would on energy running the pump at the right time.
  • Some pool pumps are loud, which could bring noise complaints. If you’re set on running your pump at night, I suggest getting a variable-speed pump. You can run it at a slow speed to reduce the noise and energy use. Furthermore, you could run it throughout the day for less money.

Is It Better to Let a Pool Pump Run All of the Time?

It’s better to let a pool pump run all of the time if you have a variable-speed pump. VSPs can run at a lower RPM, which consumes much less energy than single-speed and two-speed pumps. However, never run a VSP all of the time if it’s higher than 1500 RPMs. While VSPs save money, they can become costly with non-stop use.

Keep these things in mind if you want to run your pump around the clock:

  • Low-speed pumps can’t push suction-side and pressure-side vacuums. You’ll have to run your pump more often and at a higher speed if you want to use a vacuum. Too much speed for too long charges your bill out the roof.
  • You might have to run your pump faster if you have a booster pump. Booster pumps use a lot of RPMs, which means you’ll have to run your pump at a higher speed and another pump on the side.
  • Single-speed pumps consume a lot of energy, especially if you use them 24 hours a day. They often run around 3500 RPMs, which is almost always twice as much as your pool needs. More RPMs require more electricity, so your utility bill will skyrocket if you run the pump all of the time.
  • You should run your pump every 24 hours for as long as necessary. Your pump needs to circulate the water to dissolve the chlorine, pH adjusters, and other chemicals. Furthermore, it promotes optimal filtration to prevent algae growth.

Can You Leave Your Pool Pump Off For a Week?

You can’t leave your pool pump off for a week because your pool will get covered in algae, the pump could lock, and the filter won’t remove anything from the water.

Furthermore, leaving your pump off for more than a couple of days could let air into the plumbing.

Here’s an in-depth look at each of these issues and why they occur:

  • Algae grows when there’s no water circulation. You might’ve noticed that there’s always more algae in lakes than in streams and rivers. This process happens because algae grows much quicker when the water is stagnant. Failure to run your pump will cause the same effect.
  • Your pump’s impeller, shaft, and bearing could strip or lock. These parts rust when there’s not enough water moving over them. The oxygen and water locked on the pump’s internal components turn to rust, rendering the pump useless. You might notice loud screeching and other noises, too.
  • The filter can’t remove anything from the water if it’s still (nor will the salt system work). Your pool won’t be able to get rid of debris, algae, etc. It also can’t heat the water or dispense chlorine via in-line feeders, offline feeders, and salt cells. Filtration is an essential part of swimming pool maintenance.
  • Stagnant water evaporates quicker, so the water level could drop below the skimmer’s inlet if the pump isn’t on. When direct sunlight hits the pool, and the pump isn’t running, your pool will evaporate at least a couple of inches per day. After a few days, air bubbles will get into the pump and filter.

Pool pumps last for a long time, but their lifespan is cut in half if you don’t run them on a routine schedule. Running the pump too often or not enough will have similar effects. Make sure you rely on the previously mentioned schedule suggestions to get the most out of your pool pump.


  • Jonah Ryan

    Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he's not writing for Temperature Master, he's usually writing for his own websites, and

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