Swimming Pool (C-53) · Lesson 1 of 8

Turnover Time, Flow Rate, and Pump Head

"Turnover Time, Flow Rate, and Pump Head" is lesson 1 of 8 in the Swimming Pool (C-53) Learning Hub. It opens with "What Turnover Time Means" and works through 6 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. What Turnover Time Means
  2. The Printed Turnover Times
  3. Gallons From the Dimensions
  4. Minimum Flow Rate in GPM
  5. Residential Pumps: The Energy Code Caps the Flow
  6. Count the Inlets and Skimmers That Carry the Flow (Public Pools)

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Volume in cubic feet" through "Minimum flow".

What you'll be able to do

  • Explain the main idea of "Turnover Time, Flow Rate, and Pump Head" in plain language you can use on the exam.
  • Apply this step with confidence: "Gallons From the Dimensions".
  • Apply this step with confidence: "Minimum Flow Rate in GPM".
  • Apply this step with confidence: "Residential Pumps: The Energy Code Caps the Flow".
  • Apply this step with confidence: "Count the Inlets and Skimmers That Carry the Flow (Public Pools)".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Turnover Time: From Gallons to GPMOne public pool, sized from the printed California numbers45 ft25 ft33,662 gal5 inlets (2 + 3)4 skimmersPlan view, layout illustrativeTHE CALCULATIONVolume25 x 45 x 4.0 = 4,500 cu ftGallons4,500 x 7.48052 = 33,662 galTurnover6 h (all other public pools)Flow33,662 / (6 x 60) = 93.5 gpmInlets2 + 3 more (23,662 / 10,000) = 5Skimmers2.25 → 3 by area | 3.74 → 4 by flowMinimum flow 93.5 gpm | 5 inlets | 4 skimmersResidential check (Energy Code): 17,235 gal > 17,000, so C = 0.0082H = 0.0082 x 47.9^2 = 18.8 ft of head at 47.9 gpm2025 CBC §§3124B, 3136B.1(6), 3137B.2; 2025 CPC Useful Tables; 2025 Energy Code §150.0(p)1CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: What Turnover Time Means

2025 CBC §3102B defines turnover time as "the maximum time allowed to circulate one complete volume of the pool water through the recirculation system." It is a limit on how SLOWLY your system may move the water, so a design starts from a time, not from a pump model. The same table governs a new residential pool or spa: HSC §115928(a)(3), printed in 2025 CRC Appendix CI, requires the circulation system to provide a complete turnover "as specified in Section 3124B."

Step 2: The Printed Turnover Times

2025 CBC §3124B lists the maximum turnover time by pool type: one-half hour or less for a spa pool, one-half hour or less for a spray ground, one hour or less for a wading pool, two hours or less for a medical pool, and six hours or less for all other types of public pools. Small, hot, shallow water gets turned over fastest because bathers load it the hardest. Memorize the list in that order: 1/2, 1/2, 1, 2, 6.

The remaining 4 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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