If you are operating a cooling tower or similar system, you are probably using bromine as your primary biocide. Chlorine is a commonly used alternative.
Maintaining the correct level of biocide in the system is crucial as the biocide is controlling the level of bacteria and the risk of potential issues including legionella. Accurate testing for the level of biocide in the system is therefore extremely important.
If you are carrying out testing for bromine or chlorine biocide levels, you need to understand the effect of pH. As the pH of the water increases, more of the biocide becomes ineffective. Its very important that you adjust your test results accordingly – you could be making the assumption that your biocide levels are much higher than they actually are. The consequences of this could be very serious:
- High bacteria levels
- Increased risk of legionellosis
- Lack of compliance with HSE guidance
To pH adjust your bromine or chlorine test result, measure the pH of your water sample and use the graph below to find what percentage of biocide is effective at that pH. Then apply this correction factor to your reading.
For example at pH 8, 84% of the bromine is effective, so if your test result for free bromine is 2ppm, the corrected result is 1.68ppm.
At pH 8, just 24% of free chlorine is in the more effective form.
links to detailed guidance
Read more about pH adjustment when testing for bromine or chlorine here:
Download the PDF guide here
