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Parks & Rec Business
| Mathematics Quiz -- Calculations 1. Basic swimming pool mathematics is critical for which of the following processes? a. chemical dosing b. pump and filter sizing c. heater sizing d. all of the above The following questions are based on a community pool with the following dimensions: The pool is 42’ wide x 75’ long rectangular pool. (non- diving pool) The pool shallow depth is 3’ and has a continuous slope to 6’ in the deep end. 2. Calculate the surface area. c. 3150 square feet (Multiply 75’ x 42’) 3. Calculate the volume a. 106,312.5 gallons (Multiply 75 x 42’ x 4.5 (average depth) x 7.5 gallons/cubic foot ) 4. The local codes require a turnover rate of 6 hours, what is the flow rate? (Answer to the closest whole number) d. 295 gpm (106,312.5 gallons divided by 6 hours divided by 60 minutes) 5. The filtration system is a high-rate sand filter. A local code requires a filter media rate of 15 gallons per minute per square foot, what is the minimum required square footage of filter surface area? (Closest whole number) a. 20 sq. ft. (295 gpm divided by 15 gpm) 6. A pool has a volume of 45,000 gallons with a turnover rate of 5 hours, what is the flow rate? b. 150 gpm (45,000 gallons/ 5 hours/60 minutes) 7. Based on Question 6, what is the required filter media rate if the filter media is diatomaceous earth? d. 75 sq. ft. (divide 150 gpm/ 2 gpm/sq. ft.) 8. A public spa has a diameter of 12 feet and an average depth of 3’, what is the volume? b. 2543 gallons (3.14 x 6’ x 6’= 113 sq. ft. surface area x 3’ deep x 7.5 gallons/ cubic foot) 9. Bather load for spas is based on 10 square feet per person, what is the maximum number of bathers in the above spa? . b. 11 people (113 sq. ft/ 10 sq. ft. per bather) 10. Local code mandates a 30 minute turnover for the above spa, what the flow rate? . c. 85 gpm (2543 gallons divided by 30 minutes) 11. What is the minimum required cartridge filter surface area for the above spa? c. 227 sq. ft. (85 gpm. divided by 0.375 gpm/sq.ft.) 12. A pool contains 100,000 gallons and local codes requires as 6 hour turnover, the flowmeter reads _225_gpm. Is the pool operation meeting minimum requirements? b. no (100,000gallons/6 hrs. /60 minutes = 278 gpm) 13. One gallon of water weights ________pounds? a. 8.33 14. One BTU will heat one pound of water one degree, How many BTU’s will it take to heat a 1000 gallons spa 10 degrees? b. 83,300 BTU’s ( 1000 x 8.33 x 10 degrees) 15. Convert the answer in Question 14 to Kilowatts. a. 24.4 kW (83,300 BTU / 3412 BTU/kW) 16. A pool contains 80,000 and it has been determined that the Total Alkalinity needs to be raised 40 ppm. The chemical dosage rate using Bicarbonate of Soda is 1.4 lbs. will raise 10,000 gallons 10 ppm. How much Bicarb must be added? b. 45 lbs (1.4 lbs x 8 x 4) 17. A pool is loosing 3” of water per day. The pool is 20 x 40; 3 to 5’ deep, how many gallons of water will be lost in one day? d. 1500 gallons (20 x 40 x0 .625 gallons) x 3” 18. After chemical testing, it is determined that the free available chlorine needs to be raised 4 ppm. You are using sodium hypochlorite (liquid bleach) with a dosage as follows: 10.7 fluid ounces will raise 10,000 gallons, 1 ppm. There is 128 fluid ounces in one gallon. How many gallons will be necessary to add to a pool which is 25 x 50, 3 to 5 deep? b. 1.25 gallons (Pool contains 37,500 gallons) (10.7 fl.oz x 3.75 x 4= 160.5 fl.oz / 128 fl.oz./gal. 19. The pool has a vacuum DE filter which contains 8 grids, each grid is rectangular 3’ x 5’. What is the total filter surface area? b. 240 square feet of filter surface area (One grid is 3x 5 = 15 square ft on one side, (both sides filter the water), so one grid is 15 x 2 = 30 sq. ft. x 8 grids = 240 sq. ft.) 20 Based on 1.25 pounds of DE powder for every 10 square feet, what is the amount of DE powder for the filter in Question 19? b. 30 pounds (240/10= 24 x 1.25= 30 pounds |
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