The problematic

When chlorine, used to disinfect water in swimming pools, comes into contact with nitrogen pollutants brought in by swimmers (urine, sweat, saliva, hair, skin etc.), it generates residual compounds called chloramines (monochloramines NH2CI, dichloramines NHCI2 and trichloramines NCI3), which should not exceed the limit of 0.6 mg/litre of chlorinated water. Amongst these chloramines, nitrogen trichloride (trichloramine) is a particularly volatile compound which naturally degasses in the atmosphere of the swimming pool, especially in covered or indoor pools.

Studies carried out by the INRS (National Institute of Scientific Research) over the last several years, have shown the irritating effect of this compound, which causes irritation of the eyes and nose, as well as respiratory problems which can incapacitate lifeguards, swimming coaches and pool maintenance personnel for work. (It has been recognised as an occupational illness since 2003).

Beyond this health issue, the regulations state that the combined chlorine content (chloramines) must permanently remain below 0.6 mg/litre, going down to 0.4 mg/litre, notably when babies are present. (source: ANSES report of June 2010). ANSES is the French agency for food, environmental and occupational health and safety.)

Overview of the French rules

>> Free active chlorine content between 0.4 mg/l and 1.4 mg/l (without stabilizer) and higher than 2 mg/l (with stabilizer).
>> Combined chlorine content < 0.6 mg/l in water or 0.3 mg/m3 in the air. (ANSES recommendation June 2010).
>> pH between 6.9 and 7.7.

>> Maximum attendance: 1 person/m2 water surface.
>> Water renewal: minimum 30 litres/day/swimmer.
>> After installation of a UV dechloraminator: the local health inspection office (in France, Agence Régionale de Santé) could demand analyses of THM (trihalomethanes), TOC (Total Organic Carbon) and chloride, according to the circular letter of the French Ministry of Health, dated February 2008.



Low pressure UV dechloramination reduces the combined chlorine concentration in swimming pools through a physical effect on all organochlorine compounds present in the water (mainly monochloramine, dichloramine and trichloramine).

UVDECHLO dechloraminators obtain convincing results on combined chlorine levels. Furthermore, studies undertaken by Professor Bratchley’s team in the United States show the effect at a wavelength of 253.7 on the destruction of three types of chloramines, based on Low Pressure UV technology.

On average, the chloramine concentration in the water decreases by 80%, and the level of nitrogen trichlorides reduces by 50%.

It has been established that the use of our low pressure UV dechloraminators does not lead to augmentation of TTHMs (Total Trihalomethanes) in the water of the pool and ensures the destruction of microorganisms such as Giardia and Cryptosporidium.

Use of UV dechloraminators in indoor public swimming pools has become indispensable for many reasons: the swimmers’ comfort, the reduction in irritation of the eye concerning swimming pool personnel, such as lifeguards and swimming coaches, compliance with the directives regarding bacteria, viruses and chloramine levels.

Since 2001, more than 800 swimming pools have been equipped with our UVDECHLO technology.

>> Publication scientifique


UVDECHLO dechloraminators are entirely made grade 316L stainless steel or PEHD (High Density Polyethylene) and have integrated low pressure UV lamps with a guaranteed life span of 16 000 hrs (two years of operation).

The equipment is dimensioned according to your requirements, to obtain significant destruction of chloramines, as well as a better control of the chlorine to be injected.
The UVDECHLO dechloraminator is easy to integrate into swimming pool water recycling systems, after filtration, but before chlorine injection.

The sizing of the installation takes into account the following characteristics:
>> Maximum recycling flow rate
>> Water volume to be treated
>> Diameters of the canalisation
>> Chloramine levels
>> Frequentation

>> UVGERMI adapts to your requirements. Our equipment can be installed horizontally (standard) or vertically (option).

>> To be suitable for sea water treatment, our reactors are also available in PEHD.


We guarantee :

>> Average annual chloramine levels below 0.2 mg/l after installation of a UVDECHLO dechloraminator.
>> Lifespan of the lamps 16 000 hrs or 2 years.

UVDECHLO advantages :

>> Scientifically proven efficiency on mono- di- and trichloramines
>> Low energy consumption thanks to our low pressure UV lamps
>> Guaranteed lifespan of the lamps 16 000 hrs or 2 years
>> Operation suited to recreational environments
>> Improvement of working conditions for swimming pool personnel
>> Swim comfort
>> Better management of new water supplies
>> Low maintenance costs: operating costs are reduced to replacement of the lamps and cleaning of the quartz sleeves
>> Horizontal or vertical installation
>> Lamps can be changed without emptying the stainless steel body
>> It’s the only dechloraminator perfectly compatible with diatom filters
>> No inconveniences due to ‘removal containment’ because cleaning is not necessary
>> Manufactured in France
>> UVGERMI tests all its devices in its own test laboratory


Do low pressure UV systems destroy the whole spectrum of chloramines ?

Yes, The scientific publications on this subject are unanimous. Low pressure lamps, monochromatic at a wavelength of 254 nm, can destroy three types of chloramines. The efficiency of the destruction varies according to the type of chloramines and the UVC dose received. The publications show that for a dose of 60 mJ/cm2, approximately 8% of mono- and di-chloramines are destroyed. For trichloramines, this percentage goes up to 17%. Cycling pool water repeatedly through the dechloraminator maintains the level of chloramines below 0.2 mg/l.

Do low pressure UV systems destroy the monochloramines and thus avoid the formation of di- and trichloramines ?

No, no more than medium pressure dechloraminators! The dechloraminator, whether it operates with low pressure or medium pressure lamps, is installed in the water treatment system. It is the successive cycling through the system, several times a day, which considerably reduces the chloramine content in the treated pool.

Are low pressure lamps monochromatic ?

Yes effectively All energy produced in the UVC spectrum is delivered at exactly 253.7 nm.

Is it difficult to predict possible chemical reactions with broad spectrum medium pressure lamps ?

Yes and No Photolysis (molecular destruction by luminous radiation) depends on the following parameters: 1. The wavelength of the radiation 2. Absorption of the radiation by the compound 3. Quantum efficiency of the photolysis (percentage of photons or light elements) absorbed which serves to destroy the molecule. 4. The photon flux (the quantity of energy of this radiation: the UV dose.) In summary: to efficiently destroy a molecule, it is necessary, but not sufficient, that this molecule absorbs the UVC radiation. The quantum efficiency of the photolysis at this wavelength must also be as high as possible and finally, the photon flux must also be sufficiently energetic. A swimming pool contains innumerable organic molecules. Each one can potentially be photolyzed. By using a large number of wavelengths with different strengths, the probability of photolysis of this or the other molecule is statistically augmented. As far as we know, no scientific study has yet been published that deals with multiple wavelengths photolysis of organic compounds present in swimming pools. Therefore it is not possible to confirm that medium pressure lamps do not lead to photolysis other than that of chloramines.

Do low pressure chloramine destructors reduce the level of trichloramines in the air ?

Not directly, and no more or less than medium pressure dechloraminators. In a swimming pool, a chemical balance is established between trichloramines dissolved in the water and those in the air. If your air treatment is not efficient, i.e. if the supply of new air and the hygrometry (relative humidity) are not optimized, it will be difficult to reduce the level of nitrogen trichloride in the air. In the majority of cases however, air treatment is efficient and between 24 and 48 hours a very significant reduction of airborne trichloramines can be observed.

Does UV treatment of water modify the pH, the quantities of chlorides or the TOC (Total Organic Carbon) ?
No, During the installation of the dechloraminator, the pH can vary according to the chemical characteristics of the water in your swimming pool. But after a couple of days it will go back to its initial value. The level of chlorides and the TOC are not influenced by the dechloraminator; however, these values increase when the supply of new water reduces.
Are low pressure lamps the only lamps authorised for use in drinking water ?

Yes In France, low pressure lamps are systematically authorised for disinfection of water intended for human consumption, according to the circular letters of 1987 and 2000. Specific approval from the Ministry of Health applies to the use of medium pressure lamps (in France).

Do low pressure lamps consume less electricity? Are they energy efficient ?
Yes, Low pressure lamps have a UVC efficiency rate of 35-40% against 15% for medium pressure lamps. Even when the power is regulated, dechloraminators equipped with medium pressure lamps will always be more energy consuming than a low pressure dechloraminator for the same level of dechloramination efficiency. What’s more, in a low pressure dechloraminator, the water flow follows the lamp(s) along their entire length, which enables a duration of contact between 1 and 2 seconds. In an medium pressure dechloraminator, the flux is perpendicular to the lamp(s) and the contact duration is extremely short, inferior to 0.4 seconds. The UVC dose necessary for dechloramination is proportional to the UVC power delivered by the lamps, multiplied by the duration of contact. For an equal dose and flux, an medium pressure dechloraminator therefore needs more UVC power. More power with less efficiency implies a higher consumption of electricity.
Do low pressure lamps have a lifespan of 2 years ?

Yes We guarantee our lamps for 16 000 hours or two years, whichever comes first. When a lamp does not work, we replace it without costs. It’s a commitment to which we have adhered since 2006.

Does a defective lamp prevent a low pressure dechloraminator from functioning correctly ?
Yes/No A lamp defect in the UVDECHLO dechloraminators equipped with one or 2 lamps (up to 50 m3/hr) will inevitably result in a rise of combined chlorine levels. Concerning the other UVDECHLO dechloraminators, if one or two lamps malfunction (which is very rare and would fall under guarantee), it alters the efficiency only very slightly and the chloramine level will remain below 0.4 mg/l.
Is it necessary to use a cleaning system with low pressure lamps ?
No, not in a swimming pool. As the dechloraminator is installed after the sand filter, only particles smaller than 40 μm reach the reactor. These particles do not deposit onto the quartz sleeve serving as a thermal and electrical insulator between the lamp and the water. This is particularly true because the temperature gradient between the plasma of a low pressure lamp (= 90°C) and the water in the pool (= 28°C) is very small. This is not the case for medium pressure dechloraminators. We only integrate cleaning systems in applications for which this is necessary, for example in an industrial setting or tertiary treatment.
Can low pressure chloramine destructors generate THMs (such as chloroform) ?
No, A scientific study (thesis of Helene Hamel, Rennes University) has shown an increase in THMs of only 5% for a UVC dose of 128 mJ/cm2. The maximum UVC dose in our UVDECHLO dechloraminators is 60 mJ/ cm2, which is sufficient to destroy the three types of chloramines without leading to an increase of THMs. All our own studies in this field have confirmed this. Nevertheless, the level of THMs is closely linked to the supply of new water.
Can low pressure UV lamps, not emitting at wavelengths below 230 nm, form THMs ?

Yes/No Significant formation of THMs (5%) only takes place if the UVC dose is superior to 128 mJ/ cm2. With our UVDECHLO equipment, this is never the case.

Does a low pressure chloramine destructor create pressure loss in the piping system ?
Yes, but only a little Like all the other elements of the piping system, the dechloraminator also contributes to the pressure loss in the network. The value oscillates between 0.02 and 0.1 bar, which is negligible compared to the 0.5 bar of a dirty, clogged up filter.
Does using a UV treatment system reduce the water consumption by 50% ?
That value is common, but it is necessary to study each case separately for confirmation. One also has to remember that the level of THMs varies with the supply of new water, so it is essential to take measurements during the process of regulating the water supply.