CPO Disinfection Systems & Sanitization Methods

Question 1

What is the primary purpose of adding chlorine to pool and spa water?

Accepted Answer

To kill or inactivate harmful microorganisms and pathogens

Answer

To adjust water pH to the ideal range

Answer

To increase water clarity and remove turbidity

Answer

To balance total alkalinity levels

Question 2

Which form of chlorine is most commonly used in residential and small commercial pools due to its convenience as a slow-dissolving tablet?

Accepted Answer

Trichloroisocyanuric acid (trichlor)

Answer

Calcium hypochlorite (Cal-hypo)

Answer

Sodium hypochlorite (liquid bleach)

Answer

Dichloroisocyanuric acid (dichlor)

Question 3

According to standard pool health codes, what is the generally accepted minimum free chlorine level for a public swimming pool?

Accepted Answer

1.0 ppm

Answer

0.5 ppm

Answer

3.0 ppm

Answer

5.0 ppm

Question 4

What do chloramines (combined chlorine) in pool water indicate?

Accepted Answer

Chlorine that has combined with nitrogen-containing compounds from bathers

Answer

Excess free chlorine that has not yet reacted

Answer

A sign that the pool has too much cyanuric acid stabilizer

Answer

Properly functioning disinfection with no further action needed

Question 5

What is breakpoint chlorination, and why is it performed?

Accepted Answer

Adding enough chlorine (typically 10× the combined chlorine level) to oxidize and destroy chloramines

Answer

Adding acid to lower pH before adding chlorine

Answer

Diluting pool water by 50% to reduce total dissolved solids

Answer

Stopping chlorine addition to allow natural UV from sunlight to disinfect

Question 6

What is the ideal pH range for maximizing chlorine's disinfection effectiveness in a pool?

Accepted Answer

7.2 – 7.8

Answer

6.8 – 7.0

Answer

7.8 – 8.2

Answer

8.2 – 8.6

Question 7

Calcium hypochlorite (Cal-hypo) has approximately what available chlorine content by weight?

Accepted Answer

65–70%

Answer

12%

Answer

35%

Answer

90–95%