Why Your Swimming Pool Water Turns Green or Cloudy, and How to Fix It

Pool water problems in Delhi tend to arrive in one of two colours, and each one points to a different cause. A green pool is a sanitiser problem: the chlorine has lost the fight and algae has moved in. A cloudy pool is usually a balance or filtration problem: the chemistry has drifted, the filter is overwhelmed, or fine particles are simply hanging in the water. Reading the colour correctly is the first step, because it tells you whether to reach for shock chlorine or for pH adjustment and a clarifier. Below we break down what green and cloudy each mean, why our local conditions make both so common, and the exact sequence that gets a pool clear again.

Green versus cloudy: what each colour is telling you

The colour of your water is a diagnosis you can read at a glance. Green water, from a faint tint to a deep swamp shade, is algae. Algae spores are always present in outdoor water, and the moment the free chlorine drops too low to kill them, they bloom and colour the whole pool within a day or two. The greener and murkier it looks, the longer the sanitiser has been failing and the heavier the bloom. Cloudy water, on the other hand, stays roughly its normal blue or grey but loses its clarity, so the bottom looks hazy or disappears entirely. That haze is not algae; it is a cloud of very fine particles or minerals suspended in the water, caused by chemistry that has drifted out of range, a filter that cannot keep up, or dust and hardness that the water has picked up. In short: green is a chlorine story, and cloudy is a balance and filtration story. Occasionally a pool is both at once, cloudy first and then greening, which simply means the chemistry slipped and the algae followed.

Why swimming pools turn green in Delhi

Green almost always traces back to chlorine that could not keep up, and Delhi hands algae several advantages. The core cause is low or failed free chlorine: skip a few days of dosing, run the pump too little, or let a heat wave burn through the chlorine, and algae takes hold fast. Our long stretch of 40°C-plus days accelerates everything, because warm water both breeds algae faster and destroys chlorine quicker under strong sun. pH imbalance compounds it, because when pH climbs too high the chlorine still in the water becomes far less effective, so a pool can show a chlorine reading and still go green. The monsoon is the other big trigger: heavy rain dilutes the chlorine, dumps in organic matter and pollen, and shifts the balance overnight, which is why so many Delhi pools green up in July and August. Dust storms load the water with nutrients and debris that feed a bloom, and the region’s high TDS supply water brings in extra dissolved solids and minerals that make chemistry harder to hold steady. Put a warm, sunlit, dust-exposed pool together with even a short lapse in chlorine, and green is the predictable result.

Why swimming pools turn cloudy in Delhi

Cloudy water rarely has a single cause; it is usually two or three small things stacking up. The most common is imbalanced chemistry, especially high pH and high total alkalinity, which push dissolved minerals out of solution as a fine white haze, a bit like the way hard water clouds a kettle. Poor filtration is the next culprit: if the pump runs too few hours a day, the filter is dirty or undersized, or it needs a backwash, the water simply is not being polished, so fine matter stays suspended. Fine debris and dust are a particular Delhi problem, because pollen, construction dust and the grit that blows in during pre-monsoon storms are too small for a loaded filter to catch on the first pass. Finally, our supply water is genuinely hard and high in TDS, so every top-up adds calcium and dissolved solids; when calcium hardness runs high the water clouds readily and scale can form on surfaces and equipment. Heavy bather load, sunscreen and body oils add to the haze too. None of these is algae, which is why a cloudy pool needs balancing and filtration rather than a big slug of chlorine.

From green to clean: the step-by-step fix

Clearing a green pool works best as a sequence, done in order, not as a single big dose of chemicals. Start by testing the water so you know the pH, chlorine and alkalinity you are working with; guessing wastes chemicals and time. Balance the pH next, bringing it into the 7.2–7.6 range, because chlorine is far weaker when the pH is high and you want every gram to count. Then shock the pool with a strong dose of chlorine, sometimes called superchlorination, and do it in the evening so the sun does not burn it off before it works. With the shock in, run the filter continuously, ideally around the clock, so it can pull the dead algae out of the water. Brush the walls, steps and floor thoroughly to lift the algae clinging to the surfaces, then vacuum out the settled debris, using the waste setting for a heavy load so you are not just pushing it back through the filter. As the filter clogs with dead algae it will lose pressure, so backwash or clean it as needed and keep going. Finally, once the water turns from green to cloudy blue, add a clarifier or flocculant to gather the remaining fine haze so the filter or vacuum can remove it. A light bloom often clears in a day or two; a heavy one may need the shock repeated and several days of filtering. When a pool is deeply green with no visibility, this is the point to bring in a professional deep clean, since draining and scrubbing is usually faster and safer than chasing a swamp with chemicals.

How to clear cloudy water

Cloudy water responds to a gentler, more targeted approach than a green pool, because you are correcting balance and filtration rather than killing a bloom. Begin by testing and correcting the chemistry: bring the pH and total alkalinity back into range, since high readings are the most common reason minerals cloud out of the water. Check calcium hardness too, because Delhi’s hard supply water often pushes it high, and very hard water clouds and scales readily; if it is high, diluting with softer water can help. Next, look hard at filtration: run the pump longer, backwash or clean the filter, and make sure it is actually running enough hours a day to turn the whole pool over. For the fine dust and particles that a filter cannot catch on its own, a clarifier clumps them into larger pieces the filter can grab, while a flocculant sinks them to the floor so you can vacuum them out to waste, which is the better choice for a thick haze. Keep the surface skimmed and the strainer baskets empty so nothing keeps recirculating. Most cloudy pools clear within a day or two of balancing and steady filtration; if yours stays milky despite correct chemistry and a clean filter, the filter may be undersized or failing, which is worth a professional look.

When to call a professional for a deep clean

Some pools are past the point where dosing and filtering will win, and recognising that saves days of frustration. If the water is deep green with no visibility of the floor, if algae has turned slimy on the walls and steps, or if the pool has sat unused and neglected for weeks, a full deep clean is the faster and safer route. In those cases the load of dead algae would overwhelm most residential filters, so draining, scrubbing every surface, and refilling with balanced water gets you swimming again far sooner. A professional visit also catches the things a DIY fix misses: a filter that is undersized or failing, a pump that is not running enough to turn the water over, or persistent cloudiness driven by very high hardness from local supply. Our team handles both one-time recovery cleans and thorough deep cleans, we test the water on site, and we tell you honestly whether a treat-in-place fix or a full drain-and-clean is the better value for your pool. We do not run maintenance contracts or AMCs; if you want ongoing upkeep, we will quote what a repeat clean looks like on a visit. For a sense of what recovery and routine swimming pool cleaning costs, see our swimming pool cleaning cost guide, and remember that final pricing is confirmed after we see the pool. We clear green and cloudy pools across Delhi NCR, from South Delhi, Dwarka and Gurgaon to Noida and Ghaziabad.