Evidence quality and scope
splash! combines first-principles heat-balance equations with published pool-water treatment guidance from WHO, PWTAG, CDC MAHC, ANSI/APSP/ICC standards, and established water-treatment references.
All outputs are planning estimates. Site-specific weather exposure, bather load, water source chemistry, local regulations, and equipment differences can materially shift real outcomes.
Always verify with measured data (thermometer + test kit/strips) before making operational decisions.
Thermal model formulas
- Pool volume: circular
V = πr²d; rectangularV = xyd. - Water thermal capacity:
C = m × c_p, wherem = ρV. - Heat balance:
dT/dt = (P_heater + P_solar − UA(T−T_air)) / C. - Equilibrium temperature:
T_eq = T_air + (P_heater + P_solar)/UA. - Time constant:
τ = C / UA. - Analytical warm-up:
T(t)=T_eq + (T0−T_eq)e^(−t/τ). - Solar baseline scaling: monthly baseline irradiance scaled using extraterrestrial horizontal irradiance ratio at selected latitude.
Chemistry formulas and dosing derivations
| Quantity | Formula / Derivation | Notes |
|---|---|---|
| FC dosing from available chlorine | g product per 1000 L per 1 ppm FC = 1 / available_cl_fraction | Dichlor 56% → 1.79 g; Trichlor 90% → 1.11 g. |
| CYA side-load from stabilised chlorine | ppm CYA per ppm FC = (MW cyanurate ring / MW product) / available_cl_fraction_adjustment | Dichlor ≈ 1.05; Trichlor ≈ 0.62. |
| TA raise (NaHCO₃) | Theoretical 84/50 = 1.68 g/1000L/ppm; practical guide 1.8 | Industry guide value used. |
| CH raise (CaCl₂ ~77%) | Practical guide 1.5 g/1000L/ppm | Depends on product purity. |
| CYA raise | 1 ppm = 1 mg/L ⇒ 1 g per 1000 L per ppm | Direct mass-balance. |
| FC minimum with CYA | FC_min = max(1.0, 0.075 × CYA) | CDC MAHC FC:CYA ratio rule. |
| Combined chlorine | CC = TC − FC; breakpoint shock rough guide 10 × CC | Operational rule-of-thumb, then retest. |
Environmental assumptions used in quantity guides
- Temperature-driven FC depletion bands are used to estimate routine chlorine demand by season/location.
- Location-aware monthly climate profile (archive when available; fallback baseline otherwise) is used for monthly scheduling context.
- Hard/soft water scenario ranges are intentionally broad and marked as rough guides because local supply chemistry can vary significantly, even within the same region.
- Product quantity tables are planning aids only and should always be corrected using measured TA/pH/CH/CYA/FC/TC readings.
Primary references (official and validated)
- WHO (2006). Guidelines for Safe Recreational Water Environments, Vol 2: Swimming Pools and Similar Environments. ISBN 9789241546768.
- PWTAG (2017). Swimming Pool Water: Treatment and Quality Standards for Pools and Spas.
- CDC (2023). Model Aquatic Health Code (MAHC), 5th Edition. cdc.gov/mahc.
- ANSI/APSP/ICC 11-2019. Water Quality in Public Pools and Spas.
- DOE Energy Saver guidance for pool heating and covers (energy.gov/energysaver).
- White, G.C. (1999). Handbook of Chlorination and Alternative Disinfectants, 4th ed., Wiley.
- Wojtowicz, J.C. (2001). Effect of temperature on chemical equilibria in swimming pools. Journal of the Swimming Pool and Spa Industry.
- Taylor Technologies. Pool & Spa Water Chemistry professional reference materials.
- Open-Meteo API documentation and datasets for geocoding, forecast, and archive climate inputs.