A saltwater chlorinator produces chlorine from ordinary table salt (NaCl) dissolved in your pool water. Through electrolysis, the device splits the salt into sodium hydroxide and hypochlorous acid (HOCl)—the active sanitising compound. This eliminates the need to manually add chlorine tablets or liquid chlorine. The water feels softer, smells less and the chlorine dosing is continuous and even.
How does a saltwater chlorinator work technically?
The heart of the system is the electrolysis cell. This cell contains titanium plates coated with ruthenium or iridium oxide. When electric current passes through the plates and salt water flows over them, an electrochemical reaction takes place.
The electrolysis process step by step
- You dissolve pool salt in the water to a concentration of 3,000 to 5,000 ppm.
- The salty water flows through the electrolysis cell, which sits in the return line after the filter.
- Direct current (6 to 36 volts, depending on the model) passes through the titanium plates.
- At the anode, chloride ions (Cl-) are converted into chlorine gas (Cl2), which immediately dissolves into hypochlorous acid (HOCl).
- At the cathode, sodium hydroxide (NaOH) and hydrogen gas (H2) are produced.
The HOCl sanitises the water in exactly the same way as chlorine from tablets. The difference is that production is continuous as long as the pump runs. After killing bacteria, the HOCl breaks down and re-forms NaCl. The salt is therefore recycled in a continuous loop.
Tip
A common misconception is that saltwater pools are chlorine-free. They are not. A salt chlorinator produces the exact same active compound (HOCl) as chlorine tablets. The difference lies in the delivery method, not the end product. Learn more about chlorine in your pool .
What salt level does your pool need?
Most salt chlorinators operate optimally at 3,000 to 5,000 ppm (parts per million), which is 3 to 5 grams of salt per litre of water. For context, seawater contains roughly 35 grams per litre, so your pool is 7 to 12 times less salty.
Calculating salt for the initial fill
The formula is straightforward: pool volume in litres x desired concentration in grams per litre = required salt in grams.
| Pool volume | Salt at 4 g/l | Salt at 5 g/l |
|---|---|---|
| 20,000 litres | 80 kg | 100 kg |
| 30,000 litres | 120 kg | 150 kg |
| 40,000 litres | 160 kg | 200 kg |
| 60,000 litres | 240 kg | 300 kg |
Always use pool-grade salt (pure NaCl, 99.8% without anti-caking agents). Regular table salt contains iodine and anti-caking additives that can damage the cell. Pool salt costs approximately 8 to 12 euros per 25 kg bag.
Monitoring salt levels
Check the salt level every 2 weeks with a digital salt meter (costing 20 to 50 euros) or test strips. Salt levels drop gradually due to rainwater, splash-out and filter backwash water. Expect to add 10 to 20 kg of salt per month during the swimming season.
Advantages of a saltwater chlorinator
A salt chlorinator offers several concrete benefits over manual chlorine dosing.
Softer, more pleasant water
At 3 to 5 g/l of salt, the water feels noticeably softer on the skin. Red eyes and dry skin occur less frequently than with manual chlorine dosing. This is because the chlorine concentration remains more stable, without the peaks that follow a manual dose.
No more manual chlorine dosing
The chlorinator produces chlorine continuously as long as the pump runs. You do not need to top up tablets or measure out liquid chlorine. Free chlorine stays stable between 1.0 and 1.5 ppm without any intervention.
Less chlorine smell
The typical “pool smell” is not caused by free chlorine but by combined chlorine (chloramines). Because a salt chlorinator continuously produces fresh HOCl, chloramines are broken down more quickly. The result: less odour and less irritation.
Lower running costs long term
After the initial purchase (600 to 2,500 euros for the system, plus 300 to 800 euros for cell replacement every 3 to 7 years), ongoing costs are low. Pool salt costs around 0.30 euros per kg. Annual salt costs for a 40,000-litre pool amount to 30 to 60 euros, compared with 150 to 300 euros for chlorine tablets.
Disadvantages and considerations
In fairness, a salt chlorinator is not a perfect system. There are real drawbacks to account for.
Constant pH rise
During electrolysis, sodium hydroxide (NaOH) is produced—a strong base. This causes the pH to rise by 0.1 to 0.3 per day during active production. You therefore need to dose pH reducer regularly. Many owners pair a salt chlorinator with an automatic pH controller (from 300 euros) to solve this problem.
Corrosion risk for metal components
Salt water is more aggressive toward metals than fresh water. Grade 304 stainless steel (commonly used for ladders and accessories) can corrode at 5,000 ppm salt. Use at least grade 316 stainless steel (marine grade) for all components in contact with the water. Also check the earthing of your pool lights.
The electrolysis cell is a wear part
The titanium plates in the cell wear down gradually. After 5,000 to 10,000 operating hours (3 to 7 years) you need to replace the cell. A replacement cell costs 300 to 800 euros depending on the brand and capacity. Calcium build-up significantly shortens the lifespan.
Reduced effectiveness at low water temperatures
Below 16 degrees Celsius, HOCl production drops sharply. Below 12 degrees, most salt chlorinators stop working entirely. During the early and late season you may need to dose chlorine manually or run the pump longer.
Maintaining the electrolysis cell
Proper maintenance extends cell life by 30 to 50%. The main enemy is calcium carbonate scale on the titanium plates.
Inspection every 3 months
Remove the cell and examine the plates. White or grey deposits on the plates indicate calcium scale. A thin layer is normal, but thick build-up reduces production capacity and increases power consumption.
Descaling the cell
Prepare a solution of 1 part hydrochloric acid (31%) to 10 parts water. Submerge the cell for 5 to 10 minutes. You will see bubbling as the scale dissolves. Rinse the cell thoroughly with clean water afterwards. Repeat this a maximum of 3 to 4 times per season.
Tip
Keep calcium hardness in your pool water below 250 ppm and pH below 7.4. At higher pH and high calcium levels, scale forms much faster on the cell plates. An automatic pH controller is a smart investment in this regard.
Self-cleaning cells
Modern salt chlorinators (from around 1,200 euros) feature self-cleaning cells. These periodically reverse the polarity of the plates, causing scale to detach. This reduces but does not entirely eliminate manual maintenance. Visually inspect self-cleaning cells at least twice per season as well.
Where to install a salt chlorinator in the plumbing
The electrolysis cell should always be the last component in the return line—after the filter, heat pump and any UV treatment. The reason: chlorine is corrosive to heat exchangers and UV lamps. By placing the cell last, fresh chlorine does not pass through other equipment.
Mount the control unit in a dry, sheltered location, no more than 5 metres from the cell. Most systems operate on 230 volts and consume 50 to 200 watts depending on capacity.
For a complete overview of the water circuit and the placement of each component, read how a pool works .
Who should consider a saltwater chlorinator?
A salt chlorinator is ideal if you have an in-ground pool of at least 15,000 litres and you are tired of dosing chlorine tablets every week. You recoup the investment in 3 to 5 years through lower chlorine costs.
It is less suitable for small above-ground pools (under 10,000 litres), pools with many grade 304 stainless-steel components, or situations where water temperature regularly drops below 16 degrees. If you want to avoid chlorine entirely, read about chlorine-free alternatives .