Why Do Pools Go Green in Summer?
Green Water = Algae Growth
When your pool turns green, it's because algae has taken hold. Algae are microscopic organisms that thrive in warm, sunlit water — especially when chlorine levels drop too low. In southern Spain, the conditions for algae growth are nearly perfect from May through October: high temperatures, intense sunlight, and warm water.
How Fast Can It Happen?
In the height of summer in Axarquía, a pool can go from clear to visibly green in as little as 48-72 hours if chlorine levels crash. A combination of high UV (which destroys chlorine), high water temperature (which algae love), and any organic contamination (leaves, pollen, dust) creates the perfect storm. This is why regular, consistent chemical management is so important.
Common Causes of Green Pools
The most common causes we see are: chlorine running out between visits, pH drifting too high (which makes chlorine less effective), a clogged or malfunctioning filter, heavy organic contamination after a storm or calima, and simply leaving the pool unattended for too long. Holiday rental pools are particularly vulnerable during changeovers if there's a gap in maintenance.
How to Prevent It
The best prevention is weekly professional maintenance with proper water testing and chemical balancing at every visit. This keeps chlorine at effective levels, pH in the right range, and the filtration system working properly. It's far cheaper and easier to prevent green water than to fix it.
What to Do If Your Pool Is Already Green
Don't panic, but don't delay either. A green pool needs shock treatment, thorough cleaning, and potentially multiple visits to restore. The longer you leave it, the harder and more expensive the recovery. Contact us for a green pool assessment and we'll get it sorted.
Frequently Asked Questions
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