CPO Disinfection Systems & Sanitization Methods 3

Question 1

When chlorine reacts with ammonia in pool water (from bather waste), which harmful byproduct is primarily formed?

Accepted Answer

Chloramines (combined chlorine)

Answer

Hypochlorous acid (HOCl)

Answer

Chlorine gas (Cl₂)

Answer

Sodium chloride (table salt)

Question 2

How frequently must a CPO or pool operator test and record free chlorine and pH levels in a public pool according to typical health department requirements?

Accepted Answer

At least every 2 hours during operating hours

Answer

Once per week

Answer

Once per day at opening

Answer

Only when bather complaints are received

Question 3

What is the recommended relationship between free chlorine (FC) and cyanuric acid (CYA) levels to maintain effective sanitation in a stabilized pool?

Accepted Answer

FC should be at least 7.5% of the CYA level

Answer

FC should be at least 1% of CYA level

Answer

FC should equal the CYA level at all times

Answer

FC should not exceed 10% of the CYA level

Question 4

Bromine is often preferred over chlorine as a sanitizer for spas and hot tubs because:

Accepted Answer

Bromine remains effective at higher temperatures and higher pH levels common in spas

Answer

Bromine is less expensive per pound than chlorine

Answer

Bromine does not require any pH adjustment in spa water

Answer

Bromine kills Legionella bacteria while chlorine cannot

Question 5

What is the purpose of a 'dichlor' (sodium dichloro-s-triazinetriene) shock treatment compared to a 'non-chlorine shock' (potassium monopersulfate)?

Accepted Answer

Dichlor adds chlorine and stabilizer; non-chlorine shock only oxidizes without adding chlorine or CYA

Answer

Dichlor reduces pH; non-chlorine shock raises pH to neutralize chloramines

Answer

Dichlor is used only in spas; non-chlorine shock is only for pools

Answer

Dichlor requires 48-hour wait time; non-chlorine shock requires 72 hours

Question 6

What is 'chlorine lock,' and what condition causes it in pool water?

Accepted Answer

Reduced chlorine effectiveness due to excessively high cyanuric acid levels that bind most free chlorine

Answer

Chlorine freezing in cold weather, requiring heated storage conditions

Answer

Chlorine gas becoming trapped in the filtration system during backwash

Answer

Over-stabilization causing free chlorine to convert entirely to combined chlorine

Question 7

A CPO inspects a commercial pool and finds a combined chlorine level of 0.6 ppm. What is the most appropriate corrective action?

Accepted Answer

Perform breakpoint chlorination by shocking the pool with enough chlorine to reach at least 6.0 ppm free chlorine

Answer

Add pH increaser to raise the pH above 8.0 to convert combined chlorine back to free chlorine

Answer

Drain the pool completely and refill with fresh water

Answer

Add cyanuric acid to stabilize the existing combined chlorine