The revised DIN19643 part 1 “Treatment of Swimming Pool Water” of April 1997 specifies a maximum chlorine residual of 0.3 … 0.6 mg/l for swimming pool water, and 0.7 … 1.0 mg/l for whirl pools.
The level of chloramines is limited to 0.2 mg/l for fresh water and water in all types of pools. However for cold water plunge pools of less than 2 m³ capacity the free chlorine residual level is limited to 0.3 … 0.6 mg/l.
The contents of trihalomethanes (THM, calculated as chloroform) in pool water must not exceed 0.020 mg/l (20 µg/l). Trihalomethanes are unavoidable by-products of chlorination and are considered, like chloramines, a health hazard. .
For the other hygienic auxiliary parameters pH-value and redox voltage DIN19643, part 1 specifies also minimum and maximum levels for fresh water and pool water. For fresh water the pH should be in the range of 6.5 … 7.6, for sea water in the range of 6.5 … 7.8.
The redox voltage as a function of the pH-value should be in fresh water 750 … 770 mV in seawater 700 … 720 mV. In accordance with DIN19643 free chlorine and pH-value must be continuously measured, controlled, and recorded. For this purpose every swimming and bathing pool (exception: cold water plunge pools smaller than 2 m³) must be provided with automatically controlled metering equipment for chlorine and pH adjustment.
In accordance with DIN19643 the redox voltage must be measured and recorded by stationary analysers. It is further laid down in DIN19643 that any failure of the chlorination system must release an alarm, and that chlorination systems must include automatic cylinder change-over units in order to prevent an interruption of the chlorination, in particular by chlorine cylinders running empty.
If the hygienic auxiliary parameters laid down in DIN19643, part 1 are within the legal limits at the end of the daily opening period of the pool, the flow rate of the re-circulation can be reduced to 50 % of the normal flow rate during the off-time (e.g. at night). During this off-time metering of the flocculant can be stopped. In part 2 of DIN19643 technical data relating to the adsorption by powdered activated carbon are described.
Using the treatment cycle: Adsorption – Flocculation – Filtration – Chlorination the above specified values for chloramines and trihalomethanes can be easily reached. All the equipment and processes described above have perfectly performed in practice and meet the latest standards of science and technology.
Since more than eighty years Wallace & Tiernan stands for perfect metering, analysing, and control technology, and for substantially better water quality in municipal and leisure pools.