Why Winter Pool Maintenance Matters
Many South African pool owners make the mistake of significantly reducing pool maintenance in winter, reasoning that the pool is not being used. The result is often a green, algae-laden pool in spring that requires expensive shock treatment, chemical correction, and sometimes acid washing to restore. Consistent winter maintenance costs less in time and chemicals than corrective treatment in September.
Circulation — Run the Pump Less, But Still Run It
Water that circulates cannot stagnate. In winter, running your pool pump six to eight hours per day (compared to eight to twelve in summer) maintains adequate circulation without excessive electricity cost. Many pool timers can be adjusted seasonally.
Run the pump during daylight hours in winter to benefit from solar heat gain and UV sterilisation of the water surface. In frost-prone areas (highveld winter nights), run the pump overnight to prevent the pump and pipes from freezing — moving water is less likely to freeze than still water.
Chemical Balance
Cold water retains chemical treatments longer than warm water — pH drifts more slowly in winter. Test your water every two to three weeks rather than weekly. Maintain:
- pH: 7.2–7.6 — the most critical parameter. Outside this range, other chemicals are ineffective and the pool can become corrosive or scale-forming.
- Free chlorine: 1–3 ppm — lower than summer because UV degradation of chlorine is reduced in winter and usage is lower.
- Total alkalinity: 80–120 ppm — stabilises pH and prevents rapid drift.
- Cyanuric acid (stabiliser): 30–50 ppm — protects chlorine from UV degradation. Less critical in winter but should not drop below 20 ppm or exceed 80 ppm.
A simple test kit (R150–R400) or test strips handle these checks easily at home. For a quarterly detailed check, your pool shop can run a full water analysis for R0–R50.
Algae Prevention
Algae establish when circulation is poor, chlorine drops below 1 ppm, or pH drifts above 7.8. Winter algae tends to be less aggressive than summer algae, but it establishes during periods of neglect and can become severe. A monthly algaecide dose (follow manufacturer instructions) provides additional protection, particularly in shaded pools where sunlight sterilisation is limited.
If you see early green tinting: shock the pool with a double dose of chlorine (granular or liquid), brush the walls and floor, run the filter 24 hours continuously for 48–72 hours, and then test and rebalance. Catching it early prevents it becoming a full algae bloom requiring acid washing.
The Filter
Your sand or glass media filter requires a backwash every two to four weeks in winter (less frequently than summer due to lower bather load and debris). Check the pressure gauge — a pressure significantly higher than baseline (typically 100–120 kPa) indicates the filter needs backwashing. A thorough filter service (media replacement for sand filters is recommended every five to seven years) supports effective filtration year-round.
Leaf and Debris Management
Autumn in South Africa brings significant leaf fall in many regions. Leaves that decompose in the pool consume chlorine, raise pH, and feed algae. Net the pool daily during heavy leaf fall, or use a pool cover to significantly reduce the debris load. Leaf traps on skimmer baskets should be cleared regularly during this period.
Equipment Checks
Winter is a good time for annual equipment maintenance before the summer swim season:
- Inspect pump seals and O-rings — replace if they show cracking or weeping
- Check the filter valve O-rings
- Inspect pool light seals if you have underwater lights
- Check all pipe joints for seeping — small leaks that are hard to notice in summer become visible in winter when the pool surface is calm