CPO Water Testing and Analysis Questions and Answers

Question 1

An operator testing the pH of a recently shocked pool using a Phenol Red indicator gets a purple reading, which is off the comparator's scale. What is the most likely cause of this result?

Accepted Answer

High levels of chlorine are interfering with the reagent.

Answer

The pH is extremely high, well above 8.2.

Answer

The total alkalinity is excessively low, affecting the reagent.

Answer

The test kit reagents have expired and are no longer accurate.

Question 2

A CPO measures the Total Dissolved Solids (TDS) in a freshwater pool and gets a reading of 3,500 ppm. Which of the following issues is a direct consequence of this high TDS level?

Accepted Answer

Reduced effectiveness of the primary sanitizer, like chlorine.

Answer

A significant increase in calcium scaling on pool surfaces.

Answer

The water will automatically become acidic, lowering the pH.

Answer

The Langelier Saturation Index (LSI) will become strongly positive.

Question 3

When performing a DPD test for free chlorine, an operator observes a brief flash of pink that quickly disappears, leaving a colorless sample. What does this result indicate?

Accepted Answer

The sanitizer level is so high it is bleaching the DPD indicator.

Answer

There is no free chlorine present in the water.

Answer

The level of combined chlorine is extremely high.

Answer

The cyanuric acid level is too low to protect the chlorine.

Question 4

An aquatic facility uses an Oxidation-Reduction Potential (ORP) controller to help manage sanitation. The ORP reading is 750 mV. What does this reading primarily measure?

Accepted Answer

The activity or sanitizing strength of the oxidizer in the water.

Answer

The specific concentration of free chlorine in ppm.

Answer

The level of total dissolved solids in the water.

Answer

The pH of the water.

Question 5

A pool has been experiencing persistent algae blooms despite maintaining adequate free chlorine levels. Which of the following secondary water tests would be most useful to investigate a potential underlying cause?

Accepted Answer

Phosphates

Answer

Copper and Iron

Answer

Total Dissolved Solids (TDS)

Answer

Salt level

Question 6

During a FAS-DPD titration test for free chlorine, the water sample turns pink after adding the R-0870 powder. The operator then adds drops of R-0871 titrating reagent. The test is complete when the water in the sample vial achieves what color?

Accepted Answer

Changes from pink to colorless

Answer

Turns bright yellow

Answer

Becomes cloudy white

Answer

Turns back to a darker pink