Pool Basics for Owners
Why it goes green after rain, and what the pool man is actually doing
A private pool in this climate is not a water feature, it is a small ecosystem that is permanently trying to become a pond. Kept on top of, it is almost no trouble. Left for ten days in the rainy season, it will teach you a lesson.
What actually keeps it clear
Three things, in order of how often they go wrong:
- Circulation. The pump has to move the whole volume of water through the filter regularly. Water that is not moving is water that is growing something.
- Sanitiser. Chlorine, whether you add it directly or generate it from salt, is what kills algae and bacteria. Tropical sun destroys it fast, which is why a pool here needs more attention than the same pool in Europe.
- Balance. pH decides whether the sanitiser can do its job at all. Chlorine in badly balanced water is close to useless, which is the usual explanation for "I added chlorine and it is still green".
Rain changes everything at once
A heavy storm dumps a large volume of unchlorinated water into the pool, dilutes the sanitiser, shifts the pH, and washes dust, leaves and fertiliser off the garden and the surrounds into it. That is four problems arriving together, which is why a pool that was perfect on Friday can be cloudy on Sunday.
It is normal. What matters is that somebody tests and corrects it soon afterwards rather than a week later — algae is far easier to prevent than to clear.
Green water is a chemistry problem, not a dirt problem. Scooping and vacuuming will not fix it. Testing and correcting will. If yours has gone green, tell us rather than draining it — draining a pool in this ground water can cause its own expensive problems.
What the service visit covers
A regular pool visit is not just netting leaves. It should include testing and adjusting the water, checking and cleaning the skimmer and pump baskets, backwashing or cleaning the filter, brushing the walls and steps where algae starts, and checking that the pump and timer are actually doing what they are set to.
Between visits, the useful things an owner or guest can do are: empty the skimmer basket if it is full of leaves, keep the water level around the middle of the skimmer opening so it can actually skim, and rinse off before getting in — sun cream and insect repellent are surprisingly hard on pool chemistry.
Running costs
The pump is a steady daily draw and one of the few loads in a villa that runs every single day regardless of whether anyone is home. It is often set to run longer than it needs to. Worth reviewing — see What a Villa Costs to Run.