The phrase describes a digital tool designed to determine the necessary volume of sodium hypochlorite solution to introduce into a swimming pool to achieve a target free chlorine level. For instance, a pool owner might use this type of instrument to calculate the amount of bleach needed to raise the free chlorine level from 1 ppm to 3 ppm in a 10,000-gallon pool. The tool takes into account pool size, current chlorine level, desired chlorine level, and the concentration of the bleach being used.
Proper chlorination is critical for maintaining a safe and healthy swimming environment. This type of tool assists in preventing both under-chlorination, which can lead to bacterial and algal growth, and over-chlorination, which can cause irritation to swimmers and damage pool equipment. The rise in availability of these instruments reflects an increased focus on precision and ease of use in pool maintenance, moving away from potentially inaccurate manual estimations.