Free, Combined and Total Chlorine

Are you a pool owner or manager? If so, then you’ll want to pay attention to the free chlorine levels in your pool.

Free Chlorine

If you’re using chlorine as your biocide (rather than bromine), then it’s important to maintain adequate levels of free chlorine in your pool to reduce the risk of infection. For most types of pools, the recommended range is 0.75 – 2.00mg/l. However, if you’re using stabilised chlorine, you’ll need a bit more – between 2.50 – 5.00mg/l. Spa pools, on the other hand, have an increased risk of legionella contamination, so the recommended range is much higher at 3.00 – 5.00mg/l.

Combined Chlorine

Have you heard of combined chlorine? This is a result of the chemical pollution that can be found in swimming pools, particularly in the form of ammonia which comes from sweat and urine from bathers. When ammonia reacts with chlorine, it creates ‘chloramines’, also known as combined chlorine.

Combined chlorine is not effective as a disinfectant, and in fact, it can be more of a pollutant. Therefore, it’s essential to remove it from your pool by a combination of dilution (adding fresh water to the pool) and filtration. You can minimise the build-up of combined chlorine by encouraging the practice of pre-swim showering.

It’s crucial to keep combined chlorine levels as low as possible, ideally no more than half of the free chlorine level and certainly no more than 1.00mg/l (whichever is lower). By maintaining appropriate levels of free chlorine and minimizing the build-up of combined chlorine, you can keep your pool safe and healthy for everyone who uses it.