Disinfection

Question 1

What does ‘free’ chlorine mean?

Answer 1

Chlorine that has not yet combined with pollution.

Question 2

What does ‘combined’ chlorine mean?

Answer 2

Chlorine that has combined with pollution and is therefore no longer ‘free’.

Question 3

What does ‘total’ chlorine mean?

Answer 3

The amount of free chlorine plus the amount of combined chlorine.

Question 4

How is the free chlorine measured?

Answer 4

With the use of a DPD1 reagent and a comparator or photometer.

Question 5

How is the total chlorine measured?

Answer 5

With the use of a DPD3 reagent and a comparator or photometer.

Question 6

How is the combined chlorine measured?

Answer 6

By taking away the free chlorine reading form the total chlorine reading.

Question 7

What is the recommended free chlorine level for a swimming pool and a spa pool?

Answer 7

1 - 3 mg/l for a swimming pool

3 - 5 mg/l for a spa pool

Question 8

What is the recommended combined chlorine level?

Answer 8

No more than half the free chlorine level and also no more than 1 mg/l.

Both conditions have to be met.