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Pool Pump Won’t Turn Off? Here’s Why (+ How To Fix)

If your pool pump doesn’t turn off, it’ll send your utility bill through the roof and put unwanted wear and tear on the motor. You’ll need to fix it quickly to avoid an unnecessarily high electric bill (or a costly motor replacement).

Your pool pump isn’t turning off for at least one of these reasons:

  1. Non-stop small motor running
  2. Light switch connections
  3. Preset automation
  4. No tags on the timer
  5. Programmed internal timer

In this article, I’ll break down the multiple reasons why your pump won’t turn off and what you can do to prevent it from happening. I’ll also show you the pros and cons of running a small motor for a long time compared to using a big motor for a short time. Enjoy!

1. Non-Stop Small Motor Running

Some pool companies install small motors to run for a long time to save money. (Small motors use less energy, which costs less money on your power bill.)

Furthermore, the pool water can’t grow algae when the chemicals are moving with the water. Running the water for a longer time is naturally better.

However, if it’s literally running non-stop, you may want to do something about it.

How  To Fix

There are two things you can do:

  1. Set the pump to run for a shorter duration. Place an OFF tag on the external timer or set the stop time if your pump has an internal timer. Try the Intermatic Time Switch Trippers. This kit comes with several ON and OFF tags. Place the ON tag when you want it to start and the OFF tag when you want it to stop.
  2. Let the pump run if it has a small motor. Anything bigger than a 1HP pump shouldn’t run all day, though. Contact your local pool store to calculate what pump size you should use and how long you should run it for the climate. Most homeowners should run their pump for one hour per 10 degrees. For example, it should run for 7 hours on a 70-degree day. (Remember to use the outdoor air temperature and not your pool water’s temperature.)

2. Light Switch Connections

Some pumps connect to light switches. Turning on the switch activates the motor. If you plug your pump into a light switch and don’t turn it off, the motor won’t stop.

The problem with plugging a motor into a light switch is that it can reset the timer every time you flip it on. The pump shouldn’t be plugged into a timer or have an internal timer if it’s used with a light switch.

How To Fix

An easy fix is to simply turn off the light switch whenever you want the pump to stop running. You can also add an automatic timer to make it, so you don’t have to adjust the timer every day manually.

If you want an automatic timer, my personal favorite is the Intermatic T104 Electromechanical Timer. It’s effective and easy to set up, and comes with timer tags, wires, and a timer to get started.

To use it (or any automatic timer), wire the timer into the nearest circuit breaker box, then attach the pump motor’s wires to the timer. Place the ON and OFF tags when you want the pump to start and stop.

3. Preset Automation

Automating your pool pump makes life a lot easier, but it can also be the reason your pump keeps shutting off.

If your pool pump has automation and isn’t primed, the pump won’t pull water.

This issue causes the pump to stay on until it gets water, which won’t happen until you turn off the automation system and prime the pump.

How To Fix

Turn off the automation and prime the pump with these instructions:

  1. Turn off the pump, automation system, and circuit breaker.
  2. Open the pump lid and fill the pump basket with hose water until it’s above the suction hole.
  3. Close the lid and turn on the pump.
  4. Open the air relief valve on the filter, then close it once the water comes out to ensure there’s no air in the pump.
  5. Turn on the automation.

Automation systems can be quite complex. We suggest hiring a pool technician to program the system if you don’t know how to do it. You could also have them prime the pump while they’re there.

4. No Tags on the Timer

Pool pumps with external timers use tags to decide when the pump turns on and off.

If your pump’s timer is missing an OFF tag, it’ll never deactivate.

This problem rarely happens with internal timers because you have to choose a start and finish time. Without it, the system won’t let you create a schedule.

How To Fix

I suggest putting tags (also known as timer trippers) on your timer.

If you have an Intermatic timer (one of the most common pool pump timers available), you just need to unscrew the tag and twist the screw to close it at the desired time.

After setting the timer tags, make sure the wires from the motor are connected to the line and load sections on the electromechanical timer.

If you have a pump with an internal timer, undo the dog tags and head to the next section.

5. Programmed Internal Timer

As mentioned above, modern pool pumps often have internal timers. These timers decide when you can start and stop the pump.

If the technician who installed the pump set it to run for 24 hours a day, the pump won’t ever turn off. Furthermore, the pump could change speeds throughout the day.

How To Fix

All programmable timers are different, but most of them use similar timer settings. Here’s what you can do:

  1. Click the SETTINGS menu.
  2. Choose TIMERS or START/STOP SCHEDULE.
  3. Select which time you want to start the pump and at what speed.
  4. Select which time you want to stop the pump.
  5. Choose FINISH or COMPLETE.

Each pump will have a different vocabulary, but the results will be the same. Your pump should run at an adequate speed to handle the equipment, including about 500 extra RPMs if you have a vacuum.

Malfunctioning timers won’t turn off the pump. Contact the pump’s manufacturer if you think your pump’s timer isn’t working properly.

Additional Pool Pump Troubleshooting Resources

If you have any other issues with your pool pump, check out our other pool pump troubleshooting articles: