I Think My Salt Cell’s Not Generating Chlorine

I Don’t Measure Any Chlorine

Regardless of how you view the situation or phrase the problem - whether it’s the chicken or the egg - if you don’t have enough chlorine in the water, that’s a problem, and you need to check that your Saltwater Chlorine Generator (SCG) is producing chlorine and sanitizing your pool.

The answer might be a salt cell not generating chlorine, rapid chlorine loss due to the water chemistry, operator error (e.g. the system not being set with a high enough output / long enough run time), or some combination of the three.

Before we proceed, a few key definitions and hard facts are called for upfront. First, when you test for chlorine, you are measuring how much chlorine is left over in the pool after it sanitizes the water. In other words, if chlorine is being used up quicker than its being replenished, the net chlorine level is zero, and it can appear that chlorine wasn't present in the water in the first place).

Next, we need to have a true understanding of the three forms of chlorine that may be reported from a test.

Free Chlorine - the one that matters most - is the fully active and available chlorine that remains after sanitizing the water (as mentioned above).

Combined Chlorine - is a weak, byproduct of (formerly free) chlorine that has bound to nitrogen from ammonia and organic matter and formed chloramines. Not only does Combined Chlorine have very little sanitizing capacity, your Free Chlorine will be further taxed as it tries to oxidise the Combined Chlorine. It should be zero.

Total Chlorine - the sum of Free Chlorine and Combined Chlorine.

Saltwater Chlorine Generator

Is your Salt Cell Not Producing Chlorine?

Here’s how to know whether or not your salt chlorinator is generating properly or not:

1) Confirm that your SCG powers up, that it is turned on and not dead.

No sign of life? See how to troubleshoot a salt chlorinator with no power. Confirm that it is coming on automatically when the pump runs every day.

2) Are there any Red Lights or Warning /Error Codes?

Allow your salt chlorinator to run for 1-5 minutes after it powers on. This allows most models to have the time to perform diagnostics and activate a warning light, if there is one.

Think of red warning lights in the same way you think of red traffic lights. “Red” means stop(ped). Salt chlorinators are checking the basic requirements for producing chlorine, and these factors all have red lights associated with them - if the requirements aren’t met, a warning will occur. That signifies a halt in chlorine production. Remedy the situation to get rid of the warning(s) and the Chlorine will start being generated again. Red Lights? See how to troubleshoot a salt chlorinator with warning lights.

IMPORTANT: If you found that in either #1 or #2 Your salt chlorinator has NOT been generating chlorine, your pool is likely to be “behind the curve” and facing a growing microorganism problem (if if still invisible).

This means your water may currently be needing much higher than levels of chlorination than normal, and you should run your salt chlorinator as much as possible to get your Free Chlorine levels high enough as quickly as possible - even adding liquid chlorine if necessary to help get things back on track and prevent larger issues. BUT - If the pool looks at all green or cloudy, this may be a sign that microorganism growth has taken off. Start a Green Pool Recovery plan to quickly achieve & sustain high free chlorine levels and stop an algae bloom in its tracks.

3) Confirmation of chlorine generation

If your system powers up and you don’t get any warnings, this means that your salt chlorinator has checked it is able to correctly pass power through its cell and back to its controller, without sensing any problems. Remember that all it takes to generate chlorine is the proper amount of power and the proper amount of salinity in the water. Salt + power = chlorine generated. If the salt chlorinator senses it is not able to perform this process, it activates a warning that it's unable to generate.

However, it’s common to worry that a salt chlorinator isn’t generating correctly if you’re not measuring free chlorine in the water, so it can be reassuring to get positive confirmation that your system is working. Most models provide additional feedback you can look at. Salt chlorinators with screens on their controls will often have a diagnostic menu, where you can observe that there is power going through the cell (look for “cell current” or “cell amps”).

Salt chlorinators with only LED indicators will often have a “Generate” or “Status” light that illuminates green when all of the system’s self-checks have been passed; some models may also have a flashing light or other indication that the system is actively generating and not in a rest cycle (depending on your set chlorine output level as well as your model - check your product manual).

Salt chlorinators with only LED indicators will often have a “Generate” or “Status” light that illuminates green when all of the system’s self-checks have been passed; some models may also have a flashing light or other indication that the system is actively generating and not in a rest cycle (depending on your set chlorine output level as well as your model - check your product manual).

Salt chlorinators with clear cells also allow you to observe the chlorine generation process. When actively generating, you’ll often see a cloudy “mist” or “fog” coming off of the titanium plates (note that if your system is set to a low output and/or if your water flow rate is high, this may be harder to see, and may look different at different times).

It might also be reassuring to know that salt chlorinators essentially will provide consistent performance across their lifespan. You don’t typically have to worry that your salt chlorinator isn’t performing like it used to, or that an old salt cell is getting “weak”. When a salt cell fails, it usually occurs rapidly so that what you’ll experience is a sudden warning if there is actually an issue, and not a period when its performance is uncertain and in-between what would be expected.

Is It Generating Chlorine, But The Chlorine Levels Are Too Low?

If you’ve confirmed that your salt chlorinator is able to generate properly, these are next steps:

1. Is the Output Setting Too Low or the Runtime Too Short?


• Turn up the SCG to a higher output setting
• Extend the runtime.


2. When Were These Settings Last Adequate?


• Have temperatures been higher since then?
• Has the swimmer load increased?
• In both cases, turn up the output level.


3. Is Your SCG Too Small?


• Is the SCG rated for at least 1.5-2 times the pool size?
• Hopefully this problem wasn’t “built in” to the pool equipment pad. If so, add capacity with a larger cell or add supplemental sanitation (UV or Ozone).


4. Is This A New Cell?



Often, a pool owner replacing a failed cell develops water problems during the shutdown and the time that transpires before the new cell is installed.

Be cognizant of this when you’ve had any disruption in chlorination, because you might be facing water with higher chlorine demand compared to before the old salt cell failed.

5. Has there ever recently been a green tone to the water or any algae spotted?



Even if you’ve got the water clear again and see no algae, you may still be facing the effects of heightened chlorine demand. If you've not treated for phosphates (released into the water when the green was eliminated), you are likely again sustaining & feeding everything in the water that needs to be sanitized.

Sustained microorganisms can deplete chlorine faster than its replenished. Use a phosphate remover.

Wild Cards

Are you trying to measure chlorine at the jets or are you running the Overnight Chlorine Loss Test?

These are science experiments which ignore too many variables and make questionable assumptions about your saltwater pool. They don’t account for or isolate many important factors. Such tests may help confirm when you have a good water balance situation, but are less than helpful if you are trying to diagnose a bad situation - so don’t waste your time.

Testing Problems?

The uncertainty range is wider than you might expect with Strips subject to potential +/- ranges of 10-20%. Some test strips only report Total Chlorine which can give you a false sense of security by not alerting you to the buildup of Combined Chlorine.

In addition, to be frank, more than a few of us are not sufficiently discriminating when comparing/matching colors making strip or even reagent testing troublesome.

Additionally, you might be surprised that there are situations when you think you don’t have enough chlorine, when your chlorine level is actually high! Most common test kits (drop kits or strips which use OTO or DPD color matching) can counter-intuitively show no color at all when the chlorine is high (such as near return jets or after shocking). Make sure you don’t think you have non chlorine when you actually have plenty!

Excessive Chlorine Demand

Sanitation and Oxidation

If you’ve checked and your salt chlorinator is in fact generating chlorine, but there is not enough chlorine in the water to leave a residual level, then chlorine demand needs to be examined. It is very possible with any pool that the chlorine is depleted faster than it is being added.

The following items should each be addressed and reviewed. We need to determine the extent to which they contribute to an excessive demand from your pool for chlorine.The following items may cause chlorine to be slow-acting, “locked” and unavailable to sanitize, depleted from the water, or cause it to be quickly used up.

1. CYA aka Cyanuric Acid aka Stabilizer

CYA is a compound that serves to protect the pool’s chlorine from being stripped out by sunlight.

CYA aligns with what we will call the Goldilocks Syndrome:

• Too little (<30) means you lose chlorine to the sunlight, and
• Too much (>50) means your chlorine is weakened with no additional protection from the sun
• For most, 30-50 ppm is just right



Unfortunately, the only means of removing cyanuric acid is to drain some pool water and top up with fresh

2. pH

In this context, pH - a measure of the water’s acidity - alters the effectiveness of your chlorine. For years, the recommended range ran from 7.2 to 7.8, but the best recommendation is a target level of 7.5. We further endorse maintaining it within the tighter band of 7.4-7.6, both for its effect on the strength of your chlorine as well as its impact on general water balance.

Many pools experience a bias towards rising pH and so it is important to test and adjust pH more often than weekly and to adjust for even small changes.

3. Combined Chlorine

Combined Chlorine - is a weak, byproduct of (formerly free) Chlorine that has bound to nitrogen from ammonia and organic matter and formed chloramines. Combined Chlorine has insignificant sanitizing capacity and becomes a further drain on your Free Chlorine which seeks to oxidize it.

When levels of Combined Chlorine reach or exceed 0.5 ppm, you should shock your pool in order to oxidise the combined chlorine. It’s usually a red flag if you are accumulating Combined Chlorine, meaning that your pool may have insufficient chlorination occurring.

4. Phosphates and Nitrates

Phosphates and Nitrates can accumulate in your pool water from a variety of sources, notably fertilizer drift or runoff and organic debris. As key nutrients for algae and other microorganisms, the presence of phosphates and nitrates can fuel explosive growth in your pool’s chlorine demand.

Nitrates can only be removed from your water by draining and refilling, while phosphates can be removed with the use of phosphate removers. Fortunately, the absence of phosphates is often sufficient to offset the presence of nitrates and other nutrients. Consequently, we advise keeping your focus on managing phosphates, ideally eliminating them.

5. Algae

Green water or algae on surfaces calls for sustained high levels of chlorine to knock it out and you can’t expect routine chlorination to remedy it. Prevent, yes. Remedy, no. So if the water is currently green or you have algae on surfaces, you will need to shock the pool with additional chlorine. Subsequently, the pool should be treated with a phosphate remover.

If you previously had green water/algae, then phosphates were released into the water once the organisms died and so you should follow up by treating with an phosphate remover and help starve out any regrowth.

If we haven’t led you to and solved your issues, then we advise you to call us at (866) 766-5243 Mon-Thu: 9-4:30 or Fri: 9-3PM Central and a member of our support team will assist you.

Alternatively, request assistance online and you will be contacted by a support team member.

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