During the disinfection of pool water, disinfection by-products may be created. Nitrate, chlorate, bromate and chloride are solutes that may enter the process during water treatment. Without additional steps the concentration in the pool water will increase continuously.
The easiest but most expensive solution is to increase the fresh water amount. Another method to reduce the concentration of THM and compound chlorine is by the use of multilayer filtration with activated carbon, however the disadvantage is the high risk of filter contamination.