If your pool water looks off, smells odd, or has patches of colour on the walls and floor, something is wrong. Most pool problems give you a visual warning before they become expensive. Understanding what you’re looking at — and why — helps you act quickly and avoid unnecessary damage to your pool surface, equipment, or water balance.
Stains: What the Colour Is Telling You
Stains are one of the most misdiagnosed pool problems. Owners assume they need to scrub harder. Often, scrubbing does nothing, because the cause is chemical, not physical.
Green, Brown, or Black Stains on Plaster or Tiles
These are usually organic or metallic in origin. Green and brown marks that appear after a dust storm are often tannins and organic debris carried in the air. Cyprus sits in a zone that regularly receives Saharan dust, and those particles settle into pool water and react with the surface over time. Algae stains tend to be green and slippery to the touch. If they feel rough or are embedded into the plaster, they are more likely mineral-based.
Black staining that returns quickly after cleaning is often black algae, which roots itself into porous surfaces and is among the most stubborn pool problems to eliminate. It requires a targeted treatment approach, not just a shock dose of chlorine.
Reddish-Brown or Rust-Coloured Stains
These point to metals in the water, usually iron or manganese. Cyprus has hard water with high mineral content, largely due to the island’s limestone geology. When water is drawn from boreholes, the iron and manganese levels can be elevated. If you add a chlorine shock without first managing metal content, the oxidation reaction can leave rust-coloured staining on the pool floor and walls almost immediately. The fix is not to scrub. The fix is to use a metal sequestrant and adjust your process for shocking the pool.
White or Grey Scale Deposits
Calcium hardness in Cyprus pool water is frequently high. Evaporation during long, hot summers concentrates calcium further, leaving white crusty deposits at the waterline or on fittings. This is calcium carbonate scaling, and it is a direct consequence of hard local water combined with high UV and heat. It can be treated with a pH-lowering acid wash or specialist descaling product, but prevention through regular water balance testing is more effective than remediation.
Foam on the Surface
Foam is not dangerous in most cases, but it is a reliable signal that something is out of balance. Persistent foam that does not clear within a few minutes usually means the water has elevated levels of organic compounds. The most common sources are sunscreen, body oils, hair products, and algaecides that were applied incorrectly or at too high a dose.
Some algaecides, particularly cheaper polyquat-based products, foam heavily when agitated by jets or a pump. If foam appeared shortly after a chemical treatment, that is likely the cause. Running the pump will dissipate it over time.
If foam persists and you cannot trace it to a recent treatment, check your total dissolved solids (TDS) and cyanuric acid levels. High TDS, which builds up as chemicals are added and water evaporates, creates a condition where the water loses its ability to self-correct. In Cyprus, where summer evaporation rates are high and pools are topped up frequently, TDS climbs steadily. At some point, partial draining and refilling is the only real solution.
Cloudy Water: Three Distinct Causes
Cloudy water is probably the most common complaint, and the term covers several different problems.
Poor Filtration
If your pump is not running long enough, or your filter is dirty or undersized for the pool volume, particles accumulate in the water and scatter light. In summer in Cyprus, most outdoor pools need the pump running for at least eight to ten hours a day. If you have been running it for four or five, cloudy water is the predictable result. Backwashing the filter and extending run time often clears a mild cloudiness within 24 to 48 hours.
Chemical Imbalance
High pH is a frequent cause of cloudiness. When pH rises above 7.8, chlorine becomes significantly less effective and calcium compounds begin to precipitate out of solution, giving the water a milky appearance. This is common after heavy use, after rain, or when bicarbonate-heavy fill water is added. Testing and correcting pH is the first step, not adding more chlorine.
Early Algae Growth
Water that looks green-grey and slightly hazy is often in the early stage of an algae bloom. This is the point to act. A full shock treatment combined with brushing all surfaces and extended filtration can stop it before it becomes a visible problem. Left for another day or two in Cyprus summer heat, what was a haze becomes a green pool.
When to Call a Professional
Some of these problems are straightforward to diagnose and treat if you have test equipment and the right chemicals. Others, particularly persistent staining, recurring cloudiness despite correct chemistry, or scaling that keeps returning, point to an underlying issue with your water source, equipment, or pool surface that requires proper investigation.
If you are managing a holiday rental in Cyprus, a green or foamy pool between guest changeovers is not just an inconvenience. It reflects directly on reviews and rebooking rates.
Pool Cleaning Cyprus covers Limassol, Paphos, Nicosia, Larnaca, and surrounding areas. If your water is not right, call us or send an email. We will diagnose it properly and fix it.