Analysis of contaminant concentration in pool water as a function of filter cycle duration

The objective of this work is to analyse the concentration of pollutants in pool water depending on the duration of the filtration cycle. The research was carried out as a case study for a sports swimming pool, with a closed circuit water treatment system. Water samples collected daily in two 14-day stages were analysed. In stage 1, the filtration cycle was two days, and in stage 2 four days. On the selected days, samples taken every two hours (8.00–20.00) were also analysed. The quality of pool water was assessed on the basis of three groups of indicator: physicochemical, microbiological and micropollutants. An analysis of each parameter was carried out depending on the length of the filtration cycle. In terms of detected micropollutants, no statistically significant differences were found between results conducted in a stage 1 and stage 2. Significant differences were found in the cases of pH, redox, chloride, and nitrate concentrations, and the total number of microorganisms (TNM). With the exception of pH, redox, and free chlorine, the other indicators showed a strong tendency to concentrate between 8 a.m. and 8 p.m. It was concluded that combined chlorine and chloride may be a criterion for determining tap water requirements to supplement water losses in the pool circuit.