Building a pool in a hot climate: Morocco, Senegal, West Africa
Manufacturers’ data sheets are written for European summers. At 40 °C, with dry air, sand-laden wind and hard water, several of their recommendations no longer hold. Here is what really changes.
1. Evaporation becomes the biggest item
In a hot, dry climate, evaporation changes scale compared with a temperate climate. Over a season, it becomes the pool’s biggest water consumption item.
The deciding factor is in fact not temperature alone, but the dryness of the air combined with wind. Dry air absorbs more vapour, and wind constantly renews the saturated layer of air above the water. That is why an exposed pool loses far more than a sheltered one, at identical temperature: see the detail of evaporation losses.
The practical consequence: in these climates, a cover is not a comfort accessory, it is a first-rank piece of equipment.
2. The water chemistry runs away
Above 28 °C, the disinfectant is used up much faster and algae develop in a few hours rather than a few days. Three adjustments:
- Twice-weekly checks in the hot season rather than weekly.
- Filtration time indexed to the water temperature, not to the calendar.
- Pay particular attention to shallow zones: a submerged shallow area can be several degrees warmer than the rest of the pool, and that is where the problems start — see the month-by-month maintenance schedule.
3. Hard water and scale
Many of the regions concerned have hard water. Combined with a pH that drifts upwards — which salt electrolysis naturally accentuates — it deposits scale on the waterline, in the pipework and on the electrodes.
The reference points to hold: pH between 7.0 and 7.4, total alkalinity between 80 and 150 mg/L so that the pH stays stable, hardness around 15 °f without exceeding 25 to 30. If the alkalinity is too low the pH becomes impossible to control: you correct constantly without ever stabilising it.
4. Dust and sand
This is the most specific constraint, and the one no European manual deals with. Fine particles pass through the skimmer baskets and go straight on to load the filter.
- After a windy spell, run the filtration continuously for 24 to 48 hours.
- Watch the filter pressure: +0.3 bar above its clean value calls for a backwash, even a recent one.
- Allow for a slightly oversized filter from the design stage: it costs little at installation and pays off greatly in use.
5. Electricity: power cuts and extra cost
Where the grid is unstable, a pump that stops for several hours a day disrupts the filtration cycles. Two answers: programming that makes up the lost time rather than a fixed schedule, and a variable-speed pump which, by running longer at low speed, absorbs the interruptions better while consuming markedly less than a conventional fixed-speed pump.
Solar is also a serious option at these latitudes: sunshine is abundant and filtration is a daytime item, which fits photovoltaic production well.
What does not change
The building technique itself stays the same: custom reinforcement, concrete sprayed in successive passes, monolithic wall, steel with sufficient cover — the technique is set out here. It is the equipment and the settings that adapt to the climate, not the structure.
That is in fact what we have been doing since we settled in Marrakech: construction methods drawn from our practice in France, with choices of filtration, treatment and water management recalibrated for local constraints.