CPO Technology & Digital Tools 3

Question 1

A pool automation controller is set to feed acid when pH rises above 7.6 and stop when pH falls below 7.4. This control strategy is called:

Accepted Answer

On/Off (bang-bang) control

Answer

On/off (bang-bang) control switches the chemical feed fully on or off based on whether the measured value crosses a set threshold, without proportional adjustment.

Question 2

When an automated chemical controller experiences 'hunting' (continuous oscillation around the setpoint), the BEST corrective action is:

Accepted Answer

Widen the deadband or reduce the dosing rate

Answer

Widening the deadband (the gap between the on and off thresholds) or reducing dosing rate prevents the system from overcorrecting and oscillating around the setpoint.

Question 3

UV disinfection systems used as a supplemental treatment in pools primarily inactivate pathogens by:

Accepted Answer

Disrupting pathogen DNA with 254 nm wavelength light

Answer

UV systems use 254 nm germicidal light to damage pathogen DNA and RNA, preventing reproduction; they are especially effective against chlorine-resistant Cryptosporidium.

Question 4

An automated salt chlorine generator (SWG) will typically shut down and display a 'low salt' alarm when salinity drops below approximately:

Accepted Answer

2,700 ppm

Answer

Most salt chlorine generators require a minimum salinity of approximately 2,700–3,000 ppm to electrolyze the water efficiently and will alarm and shut off below this level.

Question 5

In a pool with an automated ozone injection system, a secondary residual sanitizer (typically chlorine) must still be maintained because ozone:

Accepted Answer

Dissipates rapidly and provides no lasting residual in the pool

Answer

Ozone is highly reactive and dissipates within seconds in pool water, so it cannot maintain a residual throughout the pool volume; a halogen residual is still required by health codes.

(CPO) Certified Pool and Spa Operator Practice Test

(CPO) Certified Pool and Spa Operator Practice Test

CPO Technology & Digital Tools 3