Home » Is Night Or Day Best To Run a Pool Pump? Plus Other Tips

Is Night Or Day Best To Run a Pool Pump? Plus Other Tips

Deciding on the best time to run your pool filter can be tricky. But not to worry. This post reveals all you should know to decide if you should run your pump in the day or night time. It also reveals some pro tips that will come in handy while deciding on when to run your pool filter. 

Let’s dive in.

Is Night Or Day Best To Run A Pool Pump?

It is best to run your pool’s pump during the day when the sun is out to reduce the risks of algae bloom and because there is generally more debris and contaminants that will enter your pool in the day. 

pool timer
pool timer

You can also run the pool filter at night to enjoy a discount on electricity and the overall cost of running a pool. 

Another option is to run your pool pump both during the day and at night too. You don’t need to run your pump in one continuous block and can run it for a few hours during the day and a few hours at night.

We recommend using a pool pump timer, that way you can set and forget it.

Why is it Best to Run a Pool Filter Pool During the Day?

Modern Swimming Pool
Swimming Pool During Day Time

Running your pool pump and filter during the day is ideal because this is when your pool is most prone to algae bloom, contaminants and chlorine loss. When the sun is out, the UV rays from the sun burn up the chlorine inside your pool.

The sun also allows algae to grow in the pool. Algae are microscopic plants that depend on the sun’s UV rays to thrive. The circulation of the water and chemicals will help to reduce algae growth.

Most people use their pools during the day. When you swim in the pool, you introduce a host of contaminants like sweat, urine, body oils, body care products, food residue, and the likes into the water. These contaminants accumulate and contribute to chlorine usage.

So you should run the pool filter after using the pool so the water can be circulated and so the contaminants inside the water can be picked up by the cartridge filters. 

These contaminants combined with the possibility of algae growth and chlorine loss means your pool is constantly under the threat of algae bloom during the day. So it’s best to run the pool filter for 6-8 hours during the day. 

But that is not all. There are a few factors that determine if you should run your pool filter during the day or at night. Let’s check out these factors below.

If You Use Pool Heating 

Pool heating is usually run during the day to maximize heating efficiency and is reliant on running a pump (although most heating systems use a second pump to circulate the water).

You should run your pool pump if you have a heat pump, solar or gas heating installed for your pool.

When to Run a Pool Pump & Filter At Night Time

Swimming pool with underwater pool lights (LED)
Swimming pool at night

Running your pool pump at night time also has some advantages. You should run the pump and filter at night if you’ve shocked the pool or are wanting to take advantage of cheaper electricity rates.

Run Your Pool Pump at Night After Shocking

You should run the pool pump for at least 8 hours at night after adding chemicals to the water or after shocking the pool. The reason for adding chemicals to the pool at night is to maximize the efficiency of the chemicals.

If you add chemicals to the water during the day, the sun’s UV rays will burn the chemicals and reduce their effectiveness. So you should add chemicals to the water and turn on the pool pump at night.

This will also ensure that the water is well circulated and the chemicals are fully mixed in the water. 

Run Your Pool Pump at Night To Reduce Power Cost

In many areas, there is usually a reduction in power cost between 9 pm and 8 am. This means you pay less for running your pool pump at night than during the day. In fact, it could be up to 60% cheaper to run your pump at night.

So to reduce the overall cost of running your pool pump, you should turn and use the pool filter at night when you can enjoy a discount on electricity costs. 

We have a whole article on calculating the cost to run a pool pump.

If You Have A Noisy Pool Pump

Having a noisy pool pump or filter can be very disturbing not just to you but to your neighbors too. So if your pool pump makes a lot of noise, you should run it during the day rather than at night because noise will seem much louder during the night time. 

When to Run a Pool Pump 24/7

Pool equipment and pump

There are some circumstances when you’ll need to run your pool pump day and night or 24 hours per day. These include having dirty pool water, having algae, shocking a pool, opening a pool or having a newly filled pool. Below is a summary but for a detailed look at the amount of time you should run your pool filter and pump, you can see our article: How Often Should You Run Your Pool Pump? And how long?

When The Pool Water Is Dirty or Has Algae

When your water is partially dirty or you have an algae problem, you’ll need to be running your pump 24/7 to speed up the time it takes to clear the water. If you do have algae, try using these products to remove it:
Shock Treatment


Usually running your pump for around 8 hours a day is not sufficient when you have algae or cloudy water. Keep filtering day and night until the water is clear.

The pool pump will circulate the water making it easier for the filter to trap debris in the water. The pool filtering process will also distribute the chemicals in the water around the pool during water circulation. 

When You Have Just Filled The Pool

You should run the pool pump for several hours during the day after filling the pool to allow the filtration system to trap any contaminant that is in the water.

Most pool owners fill their pool during the day. After filling the pool, you should run the pool filter continuously for several days to allow the water to circulate and filter, especially if you filled the pool with well water.

You should also run the pool pump after treating the water.

Final Thoughts

Overall, deciding when to run your pool filter can be tricky. Either you decide to run the pool pump during the day or at night or both. There are perks to take advantage of either way. But in the end, it’s up to you and what works for your pool.