NASCO Facility Operations & Maintenance 2

Question 1

What is the recommended free chlorine residual range for a public swimming pool in most US states?

Accepted Answer

1.0–3.0 ppm

Answer

Most US health codes require free chlorine between 1.0 and 3.0 ppm to ensure effective disinfection without causing irritation.

Question 2

Which piece of equipment is primarily responsible for removing suspended particles from pool water?

Accepted Answer

Sand or DE filter

Answer

Sand, diatomaceous earth (DE), and cartridge filters physically trap suspended particles to clarify pool water.

Question 3

A pool operator notices foamy water on the pool surface. What is the most likely cause?

Accepted Answer

Body oils, lotions, or soaps introduced by swimmers

Answer

Foamy water is typically caused by organic contaminants such as body oils, sunscreen, and soaps introduced by bathers.

Question 4

What is the primary purpose of backwashing a sand filter?

Accepted Answer

To remove trapped dirt and debris that restrict flow

Answer

Backwashing reverses water flow through the filter to flush out accumulated debris, restoring flow rate and filtration efficiency.

Question 5

At what pH level does chlorine become LEAST effective as a disinfectant?

Accepted Answer

8.0 or above

Answer

As pH rises above 7.8–8.0, hypochlorous acid (the active form of chlorine) converts to the much weaker hypochlorite ion, drastically reducing disinfection.

(NASCO) National Aquatic Safety Company Aquatic Facility Operator Certification Practice Test

(NASCO) National Aquatic Safety Company Aquatic Facility Operator Certification Practice Test

NASCO Facility Operations & Maintenance 2