Free chlorine is measured with the DPD1 test. It indicates how much of the total chlorine in the pool has not yet reacted with any pollution (ie, combined) and is therefore free and available to carry out it's purpose as a disinfectant.
There should always be enough free chlorine in the pool to minimise the risk of cross-contamination. The minimum recommended amount is 0.5mg/l. any less than this and you will need to shut the pool. The maximum recommended amount is 2.5mg/l. There is no need to have any more than this in the pool unless you are superchlorinating the pool for some reason (ie, following faecal contamination etc.)
In : Disinfection
Tags:
"free chlorine" "water testing" "dpd1"
