Technology & Digital Tools Flashcards

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:

Answer: On/Off (bang-bang) control

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.

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

Answer: Widen the deadband or reduce the dosing rate

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.

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

Answer: Disrupting pathogen DNA with 254 nm wavelength light

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

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

Answer: 2,700 ppm

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.

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

Answer: Dissipates rapidly and provides no lasting residual in the pool

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.

A pool operator notices the automated controller's flow switch is reading 'no flow' despite the pump running. The FIRST thing to check is:

Answer: Whether the flow switch paddle is clogged or stuck

A 'no flow' signal with the pump running most commonly indicates a fouled or stuck flow switch paddle, which is a simple mechanical issue to inspect before suspecting electronics.

What is the primary purpose of the 'lockout setpoint' feature found in many pool chemical automation controllers?

Answer: It stops chemical dosing if a measured parameter reaches a dangerous level

A lockout setpoint halts all chemical dosing if pH or ORP reaches a value outside a safe operating range, protecting swimmers from over-dosing accidents.