Odours can mean different things in different types of systems. Check below for your system type and odour description.
Brominated Systems:
When brominated systems are not properly balanced, it can increase the odour. When pH is too low and total bromine residual too high, the gassing off process is more active and the odour may be very strong. The fact that many brominated systems are indoor may make this seem worse. To make sure you are getting accurate test readings for pH in the wet lab, use up to 5 drops of chlorine neutraliser in the pH sample. Bromine can discolour the pH indicator reagent and make the pH reading look higher than it actually is.
Chlorinated Systems:
The most common odour for chlorinated systems is a strong chlorine-like odour. This is usually an indication that there is combined chlorine (chloramines) present, and not that the chlorine residual is too high. Check the total and free chlorine residuals and shock with 1 bag of Lite per 50,000 litres or 1 bag of Burn Out Extreme per 50,000 litres or 150 grams of Burn Out 35 per 10,000 litres for each ppm of combined chlorine.