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Free Online Swimming Pool Circulation Calculator

Calculate pool circulation flow (m³/h, L/s) and filter area from pool volume and turnover time. For public and domestic pools. Free online tool, no sign-up.

📐 Standard: IS 3328
✅ Free to use
📄 PDF export
📱 Mobile friendly
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Swimming Pool Circulation Calculator
Reference: IS 3328
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Calculate pool circulation flow (m³/h, L/s) and filter area from pool volume and turnover time. For public and domestic pools. Free online tool, no sign-up.
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Results

ℹ️ About This Calculator

A swimming pool must circulate its entire volume through the filter within a set turnover time to stay clear and safe. This calculator finds the required circulation flow and the sand-filter area from the pool dimensions, target turnover time and filtration rate.

Public pools are usually turned over every 4-6 hours; domestic pools can run 6-8 hours. The circulation flow is simply pool volume divided by turnover time, and the filter area follows from the flow and the filter's design filtration rate - about 30 m³/h·m² for a standard sand filter or up to 50 for a high-rate filter.

📐 Pool Circulation Formula

IS 3328

V = L × W × D
Q = V / T
Filter area = Q / filtration rate

V = pool volume, m³
L, W, D = length, width, average depth, m
Q = circulation flow, m³/h
T = turnover time, h
filtration rate = 30 (sand) to 50 (high-rate) m³/h·m²

🧮 Worked Example

Example: A 25 × 10 m pool with 1.5 m average depth holds 375 m³. For a 4-hour turnover, Q = 375 / 4 = 93.8 m³/h (26 L/s), which is 6 turnovers per day. At a 30 m³/h·m² sand-filter rate the required filter area is 93.8 / 30 ≈ 3.13 m², sized as one or more filters to suit.

❓ Frequently Asked Questions

How do I calculate pool circulation flow rate? +
Divide the pool volume by the required turnover time. For a 375 m³ pool with a 4-hour turnover, the flow is 375 ÷ 4 ≈ 94 m³/h. The circulation pump and filter are then sized for this flow.
What is a good turnover time for a swimming pool? +
Public and commercial pools typically require a 4-6 hour turnover; some spas and paddling pools need faster. Domestic pools can use 6-8 hours. Faster turnover means better water quality but a larger pump and filter.
How do I size a pool sand filter? +
Divide the circulation flow by the filter's design filtration rate. Standard sand filters run at about 30 m³/h per m² of bed area; high-rate filters up to 50. A 94 m³/h pool at 30 m³/h·m² needs about 3.1 m² of filter area.
How many turnovers per day does a pool need? +
A 4-hour turnover gives 6 cycles per day, a 6-hour turnover gives 4. Commercial pools generally aim for 4-6 turnovers daily; heavily used pools may need more to maintain disinfectant residual and clarity.
Does pool depth affect the circulation flow? +
Yes - deeper pools hold more water for the same surface area, so the volume and therefore the required flow increase in direct proportion to average depth. Always use the average depth across the shallow and deep ends.

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⚠️ Disclaimer: For preliminary engineering design only. Verify all results with a licensed engineer before use. Full disclaimer →