Selcoperm 125 - 2000 - Electrochlorination system



The Selcoperm is an electrolytic chlorination system. Using electrolysis, chlorine is produced directly from a solution of common salt using electricity, without creating any notable by-products. Typical disinfection applications for Selcoperm systems include:

  • Drinking water treatment
  • Swimming pool water treatment
  • Industrial treatment of cooling tower and process water.

The following reactions take place in the electrolytic cell:

2 NaCl + 2 H2O à 2 NaOH + Cl2 + H2

The chlorine produced reacts immediately with the caustic soda solution also formed, resulting in a hypochlorite solution:

Cl2 + 2 NaOH à NaCl + NaClO + H2O

The solution generated has a pH value between 8.5 and 9.5, and a maximum equivalent chlorine concentration in the range of 6-7 g/l. It has a very long half-life which makes it ideal for storage in a buffer tank. After dosing the solution into the water flow, no pH value correction is necessary, as it is often required in electrolysis according to the membrane principle. The sodium hypochlorite solution reacts in a balance reaction, resulting in hypochlorous acid, the efficient disinfectant:

NaClO + H2O à NaOH + HClO

The dosing quantity depends on the application as well as the local regulations. In general, the concentration after the injection unit is 0.3 to 2 ppm chlorine equivalent.


  • Common salt is the base material – it is nontoxic and easy to store.
  • Only water, common salt and electricity is needed for the electrolysis – low operating costs, world-wide use.
  • Fresh hypochlorite is always on hand – the disinfectant solution does not dissociate like commercial hypochlorite solutions. Lower formation of chlorate as a by-product.
  • Approved disinfection method – an alternative with less safety requirements to chlorine-gas-based systems.
  • Robust elementary components – low-maintenance and a long service life, compared with the membrane cell electrolysis.


  • Only water, common salt and electricity is needed for the electrolysis
  • Low operating costs
  • Common salt is non-toxic and easy to store



Product brochure

PURIFY YOUR BUSINESS (Product brochure)

Grundfos has a full range of products that cover the entire water cycle: supply, treatment, distribution and wastewater collection. We can deliver everything from circulator pumps and boosters right through to mechanical and digital dosing pumps with a wide variety of specifications.

Grundfosliterature-2665766.pdf (1 MB)

Data booklet

Selcoperm SES Electrolysis system for 110-1800 g/h Cl2 (equivalent)

Safe and simple production of sodium hypochlorite solution

Grundfosliterature-3279106.pdf (5 MB)

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