Maintaining a lagoon pool in the Marrakech climate
A pool that looks after itself in Normandy calls for a different routine here: the water goes above 28 °C, the wind brings sand that passes through the skimmer baskets, the mains water is hard and the level drops without anyone opening a valve. Four constraints, four settings to change.
Heat: everything speeds up
Above 28 °C, the water becomes a far more favourable medium for algae and bacteria, and the disinfectant is used up much faster. Three practical consequences:
- Filtration time must follow the temperature, not the calendar.
- Water testing goes from weekly to twice-weekly at the height of summer.
- A shallow submerged area can be several degrees warmer than the main pool: that is often where the problems start.
Dust and sand wind
This is the constraint most specific to the Moroccan climate. Fine particles do not behave like leaves: they 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: a rise of more than 0.3 bar above its clean value calls for a backwash, even if the last one was recent.
- A flocculant helps clump together particles too fine to be retained — but it cannot be used with every type of filter.
- A cover used outside bathing hours massively reduces what gets in.
Hard water
The water in the region is generally hard. High hardness, combined with a pH that drifts upwards — which salt electrolysis accentuates — deposits scale on the waterline, in the pipework and on the salt cell electrodes.
The remedy comes down to two actions: keep the pH within the recommended range without letting it drift, and watch the total alkalinity so that the pH stays stable. If the alkalinity is too low, the pH becomes impossible to control: you correct endlessly without ever stabilising it.
Evaporation
In summer, evaporation becomes an item in its own right: see what makes evaporation losses vary. Two effects to know about: the level drops until the skimmer loses its prime if you do not watch it, and the water that evaporates leaves its salts and limescale behind, which gradually concentrates the minerals. Topping up is part of maintenance, not of the unexpected.
An adapted schedule
All year round
- Empty the skimmer and pump pre-filter baskets.
- Check the water level, especially after a hot spell.
- Check the filter pressure.
From May to September
- Water testing twice a week.
- Filtration time adjusted to the temperature.
- Brushing the waterline and the submerged shallow area: that is where deposits settle.
- Cover put on as soon as the pool is not in use.
From November to February
- Filtration markedly reduced, but rarely stopped: the winter is mild and a pool that is fully shut down turns green.
- Salt cell slowed down or switched off below about 15 °C.
- Monthly check of the water balance.
What not to do
Draining the pool completely to “start again with clean water” is a bad idea: it is considerable waste in a region where water matters, and an empty pool is subject to structural stresses — especially if the water table is close. In the vast majority of cases, a corrective treatment and a good filter backwash are enough.
A proper routine takes about twenty minutes a week, provided it is set to your pool and not to a generic calendar. If you inherit a pool whose installation you do not know, start by having three things measured: the actual flow rate, the water hardness, the state of the filter.