No Flow Light On Salt Water Chlorinator Is On (Solved)

No Flow Light On Salt Water Chlorinator Is On (Solved)

Your salt water pool system has a special feature that other pools often don’t have. The feature is a water flow sensor that is inside the piping that draws attention to low water flow or no water flow so that the salt cell can immediately be shut down.

In this case, the salt chlorinator will not produce chlorine and it does this to protect the salt cell from damage. Low or no water flow through your pool pump can occur for several reasons.

The no flow light will illuminate when your salt water pool isn’t pumping enough water for the salt cell to operate safely without being damaged by a lack of water. Commonly a water flow problem is due to a side skimmer or pump basket that is full or blocked or a filter that needs rinsing or back washing.

While these are the main and most common reasons, there are other possibilities that we’ll discuss below.

Why does the no flow light illuminate in a salt water pool?

Your salt chlorinator system should come with a safety feature that will shut the chlorinator off when it detects a low water flow or no water flow at all. The salt cell is electrically charged when chlorine is being produced and it cannot run dry.

So if low water flow or no water flow is detected, the chlorinator shuts down chlorine production and the warning light turns on so you can visually see that there is a problem. The water flow sensor is build into the piping. You can typically find it near the pump so look for a wire on the piping that is attached to it. That’s usually the easiest way to locate it. It could be loose or has become damaged or disconnected.

When the water sensor detects a low water flow, the pump will continue running but the chlorinator won’t operate and thus no chlorine will be produced. This will continue until a suitable water flow is restored.

If the reason for the low water flow is a common one – the skimmer basket or side skimmer is either blocked or otherwise full – you’ll probably also hear the pump slurping and sucking air.

The main reasons the no flow light illuminates in the first place

The main reasons that water flow gets restricted and causes the no flow light to illuminate include:

  • Side skimmer basket is full and needs to be emptied.
  • Pump basket is full and needs to be emptied.
  • Pool filter needs to be backwashed (in the case of a D.E. filter or sand filter) or cartridges (in the case of a cartridge filter) need to be rinsed.
  • Pool filter medium (sand or cartridge) might also need to be replaced.
  • Salt cell might need to be cleaned or replaced.
  • Water flow sensor might need to be checked or replaced if it’s malfunctioning.
  • The pump basket lid may have come loose and is sucking air.
  • The filtration unit might be leaking i.e. check the pressure gauge, any fasteners that hold the system in place, any water release valves and caps, etc.
  • There might be a larger leak somewhere that is causing the pump to suck air rather than water.

If you see bubbles in the water coming out of the water returns, that’s a sign that you have a leak as air is making it’s way into the system.


The no flow warning light on your salt water chlorinator is a protective feature that will shut the salt cell’s chlorine production down to protect the cell from damage. Chlorine production won’t start up again until the water flow has reached the minimum level required.

Typically a low (or no) water flow is due to a blocked or full side skimmer or pump basket that needs to be emptied. It may also be due to a filter that either needs backwashing or rinsing depending on the type of filter you own.

Also check to see that the pump basket hasn’t become loose as this will let air into the system and cause water flow to drop. Learn to listen to the sounds of your pool because over time you will learn how to troubleshoot based on noise from the pump either sucking air or otherwise running improperly.

Carl Mueller

I bought a home with a salt water pool in 2006 and soon realized the benefits over traditional chlorinated pools. On this website I'll discuss all the tips and tricks I've learned over the years. I'll also help you troubleshoot various problems with pools in general and ones specific to salt water pools that I've experienced personally!

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