CPO Disinfection and Sanitizers 2

Question 1

Which chlorine product has the highest available chlorine content by percentage?

Accepted Answer

Trichlor (trichloroisocyanuric acid)

Answer

Trichlor tablets contain approximately 90% available chlorine, the highest of all common pool sanitizers.

Question 2

What is the most effective disinfecting form of free chlorine in pool water?

Accepted Answer

Hypochlorous acid (HOCl)

Answer

Hypochlorous acid (HOCl) is the active, uncharged form of chlorine that penetrates cell walls and kills microorganisms most effectively.

Question 3

Trichlor and dichlor are considered 'stabilized' chlorines because they contain:

Accepted Answer

Cyanuric acid (CYA)

Answer

Stabilized chlorines contain cyanuric acid, which binds to chlorine and protects it from UV breakdown in sunlight.

Question 4

What effect does sodium hypochlorite (liquid chlorine) have on pool pH?

Accepted Answer

Raises pH due to its highly alkaline nature

Answer

Sodium hypochlorite has a pH of 10–13, so adding it to pool water raises the pH over time.

Question 5

Which calcium-based chlorine product will gradually increase total calcium hardness in pool water?

Accepted Answer

Calcium hypochlorite (cal hypo)

Answer

Calcium hypochlorite releases calcium ions each time it dissolves, progressively raising calcium hardness levels.

CPO (Certified Pool Operator Exam) Practice Test