Salt Chlorinator: Function, Installation, Salt Level and Maintenance
A salt chlorinator continuously produces the disinfectant itself from dissolved salt, replacing the need to add chlorine by hand. That does not make it chlorine-free, however – this article explains how it works, how to integrate it after the heater, the salt level, cell cleaning and material compatibility.
How a salt chlorinator works
With a salt chlorinator, ordinary table salt (sodium chloride) is added to the pool water in a low concentration. The salted water flows through an electrolysis cell with coated titanium electrodes to which the control unit applies a DC voltage. At the electrodes, the dissolved chloride is converted into active chlorine, or hypochlorous acid – exactly the active agent you would otherwise add as chlorine granulate or tablets.
Important for those switching from chlorine: salt water does not mean chlorine-free. The chlorine produced in the cell disinfects in exactly the same way; it is simply generated continuously on site instead of being dosed by hand. In the pool the water tastes only slightly salty, because the concentration is far below that of sea water.
After disinfection, part of the chlorine recombines into chloride – so the process largely runs in a closed loop. As a result, very little salt is consumed; it is essentially lost only through dilution, backwash, filter cleaning and splashing.
Salt chlorinator or conventional chlorination?
If you are switching over, a sober comparison of the two approaches is worthwhile. Above all, a salt chlorinator reduces the daily manual work, but it replaces neither pH control nor regular water analysis.
| Criterion | Salt chlorinator | Conventional chlorination |
|---|---|---|
| Chlorine generation | continuously from salt in the water | manual addition of chlorine products |
| Daily effort | low, largely automatic | regular dosing and refilling |
| Chemical storage | bags of salt instead of chlorine | chlorine granulate or tablets |
| Purchase cost | higher (cell plus control unit) | lower |
| pH behaviour | tends to rise, pH control recommended | varies depending on the product |
| Material environment | salt water slightly corrosive, check metal parts | depends on the chlorine product |
Automatic pH control is almost always worthwhile with a salt chlorinator, because the process drives the pH value upwards and otherwise the effectiveness of the chlorine drops.
Installation sequence in the plant room: the cell comes last
The electrolysis cell is integrated into the pressure or return line – as the last piece of equipment, just before the water flows back into the pool. This is what the sensible sequence in the plant room looks like:
- Suction (skimmer, main drain) to the pump with pre-filter
- Filter (sand filter or alternative)
- Heater or heat pump
- Measurement, control and dosing technology (pH control)
- Electrolysis cell
- Return through the inlet nozzles into the pool
The cell is deliberately located after the heater: it works with water that has already been filtered, and the freshly produced, more highly concentrated chlorine no longer passes through the heat exchanger. For cleaning and inspection, install the cell with one union before and one after the housing, so that it can be removed without cutting. Observe the prescribed flow direction and – if present – the position of the gas separator (electrodes/gas side facing up). Depending on the system, the connections are OD d50 (DN40) or OD d63 (DN50); adapt the cell to your existing line with short fitting pieces.
The electrical connection and equipotential bonding of the control unit (230 V, residual-current protection) belong in the hands of a qualified electrical contractor and must comply with the relevant regulations for swimming pools.
Setting the salt level and topping up salt correctly
Every system states its target value in the data sheet. Depending on the design, common systems operate in the range of roughly 3 to 6 g/l; particularly economical low-salt units need less. Stick to the manufacturer’s value – too little salt reduces chlorine production, too much places an unnecessary strain on the material and the cell.
For the initial fill, calculate the amount of salt from the pool volume and the target value. Use high-purity pool salt without additives – no de-icing salt, no salt with anti-caking agents or iodine. Spread the salt evenly into the pool with the circulation running, not into the skimmer, and let it dissolve completely before starting the cell.
You only need to top up salt when the level has dropped due to fresh water, backwash or splashing. Many control units display the salt level; nevertheless, check it regularly with a test strip or meter and top up in small increments.
Recognising cell scaling and cleaning the cell
The most common loss of performance is caused by limescale deposits on the electrodes. It insulates the plates and reduces chlorine production. With hard fill water this occurs more quickly. Many cells have a self-cleaning polarity reversal (reverse polarity) that reduces deposits, but does not completely prevent them with hard water.
Depending on the water hardness, inspect the electrodes visually for white deposits at regular intervals. To clean them:
- Disconnect the cell from the power supply and remove it via the unions.
- Dissolve the deposits with a suitable cell cleaner or heavily diluted acid according to the manufacturer’s instructions.
- Then rinse thoroughly with clean water.
Never scrape mechanically and do not use metal tools – the electrode coating is delicate and would otherwise be permanently damaged. A stable water hardness and a properly functioning pH control significantly extend the cleaning intervals.
Material compatibility in the pool and its surroundings
Salt water is somewhat more aggressive towards metals than normally chlorinated fresh water. Plastic components such as PVC-U pipes, fittings and valves are harmless and permanently resistant to salt water. The metal parts, on the other hand, deserve attention:
- Stainless steel built-in parts (ladders, handrails, counter-current jets): higher-grade alloys are more suitable for salt water – clarify their suitability with the manufacturer of the built-in part.
- Natural stone and metal edging can be attacked by splashing.
- If different metals are combined, galvanic corrosion can occur; depending on the system, a sacrificial anode helps here.
Before converting an existing pool, check that the liner, built-in parts and existing metal parts are approved for salt water operation. If in doubt, have the material compatibility and the equipotential bonding assessed by a specialist company before you add salt.
Installing and commissioning a salt chlorinator
- Choose the installation location Plan the cell as the last piece of equipment after the heater in the return line, with enough space and accessibility for later cleaning.
- Cut the line and prepare fitting pieces Cut the pressure line at the chosen point and cut short fitting pieces from OD d50 or OD d63 pipe to match the cell connection.
- Install the unions Clean and degrease the pipe ends and solvent sockets, solvent-cement one union before and one after the cell, and let the cemented joints cure before water is introduced.
- Fit the cell Mount the cell between the unions and observe the prescribed flow direction as well as the position of the gas separator.
- Electrical connection by a specialist company Have the qualified electrical contractor carry out the connection of the control unit (230 V, residual-current protection) and the equipotential bonding in accordance with the applicable regulations.
- Add and dissolve the salt Calculate the amount of salt from the volume and target value, spread high-purity pool salt into the pool with the circulation running and let it dissolve completely.
- Set up and check the control unit Calibrate the salt value, start production and, after a few hours, check the chlorine level and pH value, readjusting if necessary.
Bill of materials
Example – please verify with a specialist. Parts and quantities depend on the installation; sizes shown are examples.
| Component | Size | Art. No. | KLN No. | Qty |
|---|---|---|---|---|
| Union Ocean, solvent socket / solvent socket | d50 | 170397 | 51512461 | 2 |
| PVC-U pressure pipe with socket | d50 | 76910 | 51515804 | as needed |
| Griffon cleaner / degreaser | – | 1 | ||
| Griffon UNI-100 PVC-U adhesive | – | 20023 | 51512566 | 1 |
| Salt electrolysis system (electrolysis cell with control unit) | – | – | – | Main component; the cell is tied into the return line as the last unit after the heater |
| Pool salt (high-purity evaporated salt without additives) | – | – | – | For initial filling and topping up; no road salt, no salt with iodine or anti-caking agent |
FAQ
Is a salt water pool really chlorine-free?
No. The system continuously produces chlorine from the salt as a disinfectant. You save the manual addition of chlorine, but the water still contains free chlorine.
How much salt does my pool need?
That depends on the pool volume and the system's target value, usually around 3 to 6 g/l. The exact target value is stated in the data sheet of the respective electrolysis cell.
Where in the plant room is the cell installed?
In the return line as the last piece of equipment after the filter, heater and pH control. This way only filtered water passes through and the fresh chlorine does not strain the heat exchanger.
How often does the cell have to be cleaned?
This varies depending on the water hardness and polarity-reversal function. Check the electrodes regularly for limescale and clean them with diluted acid when necessary, never mechanically.
Can I convert an existing pool to a salt chlorinator?
As a rule yes, provided the liner, built-in parts and metal parts are approved for salt water. Check this beforehand and have the electrical connection carried out by a specialist company.
This guide provides general technical orientation and does not replace professional planning. Safety-, electrical- and permit-relevant work must be carried out by qualified specialists.
