Water Testing and Analysis Flashcards

What is the recommended pH range for public swimming pool water according to standard CPO guidelines?

Answer: 7.2–7.8

The CDC and PHTA recommend maintaining pool pH between 7.2 and 7.8 for effective disinfection and swimmer comfort.

What is the standard target range for total alkalinity in a public swimming pool?

Answer: 80–120 ppm

Total alkalinity should be maintained between 80 and 120 ppm to stabilize pH and prevent rapid fluctuations.

Which of the following does a DPD (N,N-diethyl-p-phenylenediamine) test kit measure?

Answer: Both free chlorine and total chlorine

DPD reagents measure free chlorine directly; adding a second reagent (potassium iodide) allows measurement of total chlorine to calculate combined chlorine.

What is the recommended calcium hardness range for swimming pools to prevent corrosion and scale formation?

Answer: 200–400 ppm

Calcium hardness between 200 and 400 ppm protects pool surfaces from corrosive low-calcium water and prevents scale deposits from high-calcium water.

When using a DPD test kit, the presence of free chlorine causes the water sample to turn which color?

Answer: Pink or red

DPD reagent reacts with free chlorine to produce a pink-to-red color; the deeper the color, the higher the chlorine concentration.

The OTO (orthotolidine) reagent tests for which water parameter?

Answer: Total chlorine

OTO reacts with all forms of chlorine (free and combined) and turns yellow, measuring total chlorine; it cannot differentiate free from combined chlorine.

When collecting a pool water sample for chemical testing, where should the sample be taken?

Answer: At elbow depth (about 18 inches) away from return inlets and skimmers

Sampling at elbow depth away from inlets and returns provides a representative mid-pool reading unaffected by concentrated chemical inputs.