CPO Pool Calculations and Formulas Questions and Answers

Question 1

An L-shaped swimming pool consists of two rectangular sections. The first section measures 40 ft long by 20 ft wide. The second section measures 30 ft long by 15 ft wide. If the entire pool has an average depth of 5 ft, what is the total volume in gallons? (Use 7.48 gallons per cubic foot)

Accepted Answer

46,750 gallons

Answer

To find the volume, first calculate the surface area of each rectangular section and add them together. Section 1 Area = 40 ft * 20 ft = 800 sq ft. Section 2 Area = 30 ft * 15 ft = 450 sq ft. Total Surface Area = 800 + 450 = 1,250 sq ft. Next, calculate the volume in cubic feet: 1,250 sq ft * 5 ft average depth = 6,250 cubic ft. Finally, convert to gallons: 6,250 cubic ft * 7.48 gal/cu ft = 46,750 gallons.

Question 2

An operator needs to calculate the filter surface area for a round high-rate sand filter that has a diameter of 36 inches. What is the correct filter surface area in square feet?

Accepted Answer

7.07 sq ft

Answer

The formula for the area of a circle is π * r². First, convert the diameter from inches to feet: 36 inches / 12 inches/foot = 3 feet. Next, find the radius, which is half the diameter: 3 feet / 2 = 1.5 feet. Finally, apply the area formula: 3.14 * (1.5 ft)² = 3.14 * 2.25 sq ft = 7.065 sq ft, which rounds to 7.07 sq ft.

Question 3

A public pool with a volume of 75,000 gallons has a measured Total Alkalinity (TA) of 40 ppm. To reach the desired level of 100 ppm, how many pounds of sodium bicarbonate are required? (Dosage factor: 1.4 lbs of sodium bicarbonate raises TA by 10 ppm in 10,000 gallons)

Accepted Answer

63.0 lbs

Answer

First, find the required TA increase: 100 ppm (desired) - 40 ppm (actual) = 60 ppm increase. Next, determine how many 10 ppm increments this is: 60 ppm / 10 ppm = 6 increments. Then, calculate the amount needed for 10,000 gallons: 6 increments * 1.4 lbs = 8.4 lbs. Finally, scale this for the pool's total volume: 8.4 lbs * (75,000 / 10,000) = 8.4 lbs * 7.5 = 63.0 lbs.

Question 4

Using the Langelier Saturation Index (LSI) formula and the provided factors, what is the LSI for a pool with the following readings: pH = 7.2, Temp = 76°F, Calcium Hardness = 200 ppm, Total Alkalinity = 50 ppm, and TDS < 1000 ppm? (Formula: LSI = pH + TF + CF + AF - 12.1; Factors: TF=0.6, CF=1.9, AF=1.7)

Accepted Answer

-0.7

Answer

Substitute the given values and factors into the LSI formula: LSI = 7.2 (pH) + 0.6 (Temperature Factor) + 1.9 (Calcium Factor) + 1.7 (Alkalinity Factor) - 12.1. Sum the factors: 7.2 + 0.6 + 1.9 + 1.7 = 11.4. Complete the calculation: 11.4 - 12.1 = -0.7. An LSI of -0.7 indicates the water is slightly corrosive.

Question 5

A 120,000-gallon public swimming pool is required by the local health code to have a turnover rate of 6 hours. What is the minimum required flow rate in gallons per minute (GPM) to meet this code?

Accepted Answer

333 GPM

Answer

The formula for flow rate is: Flow Rate (GPM) = Pool Volume (Gallons) / Turnover Rate (Hours) / 60 (Minutes/Hour). First, find the gallons per hour (GPH): 120,000 gallons / 6 hours = 20,000 GPH. Then, convert GPH to GPM: 20,000 GPH / 60 minutes/hour = 333.33 GPM, which rounds to 333 GPM.

CPO (Certified Pool Operator Exam) Practice Test

CPO (Certified Pool Operator Exam) Practice Test

CPO Pool Calculations and Formulas Questions and Answers