Why Is My Chlorinator Not Making Chlorine? 5 Tests in Order

Name: comparepoolquotes
Price range: $$$

Why is my chlorinator not making chlorine? Usually not a dead cell: low salt, water below 15°C and scale on the plates all cut output and cost little or nothing to fix. A worn cell is the costly answer; two major makers put cell life at 10,000–20,000 hours, or roughly 3–5 years. Test the cheap causes first.

The short answer

Test 1, settings and stabiliser: $0. Two chlorinator makers' manuals list a short timer, a low output setting and low stabiliser (they say keep it at 30–60 ppm) as causes of low chlorine.
Test 2, salt: use an independent test. Minimums differ by unit: 3,000 ppm on one maker's unit, 4,000 on another's, 4,500 on a third's. One maker says its display is only accurate to within 500 ppm.
Test 3, water temperature. Below 15°C, low-salt warnings are expected on two makers' units; two manuals say to switch the cell off below 10°C.
Test 4, the plates. White scale lowers output. HealthyWA says it is worse where calcium is high; the manuals say a cell-cleaning soak of about 10 minutes removes it.
Test 5, cell age. 10,000–20,000 operating hours per two makers' guides. At 8 hours a day in summer and 4 in winter, that is about 4.6 to 9.1 years.

The five-test chlorinator check, cheapest first, with the thresholds from Australian chlorinator manufacturers' manuals (read 30 September 2026)
Test, in this order	What you need	Points to	Threshold from the manuals	Fix and what it costs
1. Settings and stabiliser	The controller, and a stabiliser test	Chlorine not being made long enough, or burned off by sun	Two manuals list a short timer, low output setting and low stabiliser as causes; stabiliser 30–60 ppm	$0 to adjust; stabiliser if low
2. Salt	Pool-shop test or salt strips, not the chlorinator's own display	Low salt after rain, backwashing or splash-out	Unit minimums differ: 3,000 ppm (one unit), 4,000 (another), 4,500 (a third)	Add salt: 10 kg per 10,000 L raises it about 1,000 ppm
3. Water temperature	A pool thermometer	Cold-water cut-back, not a fault	Low-salt warning below 15°C (two makers); switch the cell off below 10°C (two manuals)	$0: lower output; add salt only within the unit's maximum; dose chlorine by hand
4. The cell plates	Switch off, remove the electrode, look	Scale insulating the plates	White crust; calcium hardness above the maker's range, e.g. 200–275 ppm for concrete pools (one manual)	Cell-cleaning solution, about 10 minutes soak (two manuals)
5. Cell age	Cell-hours counter, or the install date	Worn plate coating	10,000–20,000 hours (two makers' guides); one maker counts a cell failed below 80% of maximum current	Replacement cell; one parts retailer listed generic cells at $245–$1,175

Why is my chlorinator not making chlorine? Five tests, cheapest first

The chlorinator manuals we read all have troubleshooting tables, and they list the same causes: settings, salt, temperature, scale, and a worn cell. The Zodiac EL series manual's entry for a low-salt warning gives four causes in one line: salt too low, water temperature low, cell calcified, cell failed. Davey's EcoSalt manual lists heavy rain, a scaled cell, cold water and a failing cell. From the pool, all of these look the same: no chlorine.

No manufacturer publishes how often each cause is the answer, so we will not rank them by frequency. The table above is ordered by what it costs you to test and fix, because that is the order that saves money: the first three cost nothing to check, the fourth costs a bottle of cleaner, and only the fifth needs a new part.

Before any of them, one free check from Zodiac's troubleshooting guide: run the chlorinator at 100% output and see whether you can see mist coming off the cell. If you can, the cell is producing, and the cause is more likely further up the list than a dead cell.

The quotable version: a chlorinator that has stopped making chlorine is more often starved of salt, cold or scaled than worn out, and those three cost little or nothing to fix.

If the pool is already green or cloudy, see why a pool turns green or why a pool goes cloudy for getting the water back while you test the chlorinator.

Is it low salt? Why the chlorinator's reading can be wrong

Salt is not used up by the chlorinator. It is lost through backwashing, splash-out, overflow and leaks, and diluted by rain; Davey's and Hayward's manuals both say it is not lost to evaporation. So a low-salt warning after a wet week or a big backwash is expected.

The catch is that the warning light is not a salt test. Davey's EcoSalt manual says its low-salinity indicator is not a temperature-compensated instrument: it is accurate to within 500 ppm and depends on water temperature, as the cell does. Zodiac's EL series manual adds that calcium on the cell's sensor can trigger a low-salt indication. Get the salt measured independently before adding any.

Then compare it with your unit's minimum, because the minimums differ:

AstralPool Viron eQ: about 4,000 ppm, never below 3,000.
Waterco Hydrochlor ST and MK3: 4,000 to 6,000, optimum 5,500.
Davey EcoSalt (2015 manual): 4,500 to 6,000. Davey's newer EcoSalt2: 3,000 to 6,000, or 1,500 to 6,000 on its low-salt models.
Zodiac EL series: warns that running below 3,000 ppm may damage the cell and void the warranty.

The manufacturers disagree on one quick test. Zodiac's online guide suggests throwing a handful of salt into the skimmer to see if the warning clears; AstralPool's eQ manual warns not to put salt directly in the skimmer box. Follow your own unit's manual.

A low-salt light is a reason to test the salt, not a reason to add it. The full range table and the salt arithmetic are on what salt level a pool should run at.

Does a chlorinator work in cold water? What each manual says

Less well, and some not at all. Cold water carries less electrical current through the cell, so the unit reads it as low salt and produces less. The behaviour differs by brand:

AstralPool Viron eQ: operating range 10–40°C. The low-salt light ‘may appear as the water temperature decreases’ below 15°C. For winter, the manual says running is safe above 10°C and the cell needs to be deactivated below 10°C.
Zodiac EL series: operating range 10–40°C, deactivate below 10°C. It needs about 6,000 ppm at 15°C against 4,100 ppm at 25°C for maximum efficiency.
Davey EcoSalt2: cold water below 15°C triggers its add-salt alarm. Extra salt can compensate, within the maximum, and ‘if water temperature drops too far, the system should be turned off’. The manual gives no figure for ‘too far’.
Waterco Hydrochlor ST: the manual we read gives an upper limit, water not exceeding 35°C, and no low-temperature figure.
Hayward AquaRite (a US-market manual): stops generating below 50°F, which is 10°C.

In an Australian winter, a chlorinator showing low salt in water under 15°C is usually behaving as designed, and adding salt to clear the light can push the level past the unit's maximum. AstralPool's and Zodiac's manuals say to add salt and turn the output down until the water is warmer, and Davey's says to keep the maximum salt level in mind while doing it. Hand-dosed chlorine can hold the level meanwhile. Pump hours for winter are on how long a pool pump should run each day.

Is the cell scaled? Checking and cleaning the plates

HealthyWA says salt chlorinators ‘are susceptible to producing a build-up of white-coloured scale on the electrodes, particularly if the water contains high levels of calcium’, and that scale reduces chlorine production. Davey's manual lists what drives it: calcium hardness, water temperature, pH control, long use of calcium hypochlorite, and calcium from the plaster of a concrete pool. It says bore water can mean cleaning as often as weekly.

The check is visual. With the pump and chlorinator off, remove the electrode and look for a white crust between the plates. AstralPool's and Zodiac's manuals both say to soak it in cell-cleaning solution for about 10 minutes, without immersing the terminals, then rinse. Self-cleaning (reverse-polarity) cells scale less but are not immune.

Prevention is calcium control. Davey's EcoSalt2 manual sets calcium hardness at 200–275 ppm for concrete and tiled pools and 100–225 ppm for other surfaces. SA Health's home-pool guidance is 150–400 mg/L.

A cell that scales every week is telling you about the water's calcium, not about the cell.

Is my chlorinator cell dead? The cell-life arithmetic

A cell wears out by design. Davey's manual says electrolysis ‘will wear away its delicate coating, at which time it gradually ceases to produce chlorine.’ What the makers publish about how long that takes:

Zodiac's and AstralPool's troubleshooting guides: ‘most cells have between 10,000 and 20,000 hours of operation’, and cells ‘generally last 3–5 years, sometimes more or less’.
One range shows a ‘TEST CELL’ message after 9,000 cell operating hours, per the same guides.
Davey: a cell is considered failed when it draws less than 80% of its maximum current, which a technician can measure.

Worked through, so you can use your own hours. Davey recommends running its EcoSalt2 6–8 hours a day in summer and 4 in winter. Take 8 hours for 182 days and 4 hours for 183 days: 1,456 + 732 = 2,188 hours a year. Then 10,000 ÷ 2,188 = 4.6 years and 20,000 ÷ 2,188 = 9.1 years. At 8 hours every day of the year (2,920 hours), it is 3.4 to 6.8 years. The hours figures and the makers' own ‘3–5 years’ overlap only at the low end, so plan on the shorter figure.

What it costs. One Australian online parts retailer's replacement-cell listing, read on 30 September 2026, priced mostly generic (non-original) cells for common units from $245 to $1,175, depending on the model and size. Genuine cells and fitting are extra to check. How the cell's price decides whether salt is worth it is worked through on saltwater vs chlorine pools.

One more possibility: the chlorinator may simply be too small. HealthyWA notes some domestic units cannot keep up in heavy use, and Waterco's manual rates one 20 g/h cell for 60,000 litres in a temperate climate but 48,000 litres in the tropics. When you replace a unit, ask for its rated pool volume for your climate, and compare pool quotes on the same specification. Pool equipment explained lists what the chlorinator line of a quote should state.

Replace the cell only when salt, temperature and scale have been ruled out, because a failed cell and a starved one look the same from the pool.

Common questions

How long does a salt chlorinator cell last?

AstralPool says roughly 3 to 5 years, depending on use. Its and Zodiac's troubleshooting guides say most cells have 10,000 to 20,000 hours of operation. At 8 hours a day in summer and 4 in winter, that works out to about 4.6 to 9.1 years.

Does a salt chlorinator work in winter?

Output falls in cold water. AstralPool's and Zodiac's manuals give an operating range of 10 to 40°C and say to deactivate the cell below 10°C. Davey's EcoSalt2 raises its add-salt alarm below 15°C. Lower the output and dose chlorine by hand until the water warms.

Why does my chlorinator say low salt when the salt is fine?

Usually cold water, scale or an ageing cell. Zodiac's EL series manual lists low temperature, a calcified cell and a failed cell alongside low salt. Davey's EcoSalt manual says its indicator is accurate only to within 500 ppm and depends on water temperature. Confirm salt with an independent test.

How do I know if my salt cell is bad?

Rule out the cheap causes first: salt confirmed in range by an independent test, water above 15°C, plates clean. If it still will not produce chlorine, check the cell's operating hours against the 10,000 to 20,000 hours makers cite, or have a technician measure its current; Davey counts a cell failed below 80% of maximum.

How much does a replacement chlorinator cell cost?

It depends on the unit. One Australian online parts retailer listed mostly generic replacement cells for common chlorinators at $245 to $1,175 on 30 September 2026. Original-equipment cells and fitting cost extra, so get the price for your model before deciding between a new cell and a new unit.

Sources

General information only, current at 2026-09-30. Pool rules differ by state and by council, and penalty amounts are updated regularly. Confirm your own obligations with your council or a registered inspector before acting.