Method and composition for use in the cyclic process for the efficient generation of chlorine dioxide in dilute solutions

1) A method for determining the relative bromide ion concentration in an aqueous system of an aquatic facility using the cyclic process, the method comprising:

• a composition comprising a bromide donor and a tracer;
• the composition is applied to the aqueous system to sustain a bromide ion concentration ranging from 2 ppm to 5000 ppm;
• the tracer is monitored to determine the relative concentration of bromide ion, and the bromide ion concentration is sustained to ensure the cyclic process and subsequent microbiological efficacy is achieved.