Table of Contents
The short answer
Green water is algae. It grows when the sanitiser in the pool has been too low for too long, usually helped by heat, a pump that stopped or a filter that was not keeping up. Cloudy water is something else: fine particles hanging in the water because the filter is not removing them, because the water is out of balance, or because a dusty wind has just dropped more into the pool than the filter can catch. Cloudy water can also be the first stage of green.
Neither is normally cured by emptying the pool, and neither is cured by tipping in more chlorine and hoping. The cure has an order. Keep everyone out. Take out the debris. Brush every surface. Get the filter working. Have the water tested and treated according to the test. Then filter, and clean the filter, until the floor is clearly visible again. The work takes hours and the waiting takes days.
A pool that has turned is one of the situations the pool cleaning and maintenance service at IHR Dream Cleaning is for. Our service page describes cloudy or green water as usually an algae or chemical-balance issue, resolved with cleaning and correct dosing, not by draining the pool. A reset of this kind is quoted by the pool's size and condition, from photos or a free inspection, before any work starts.
Read the water before anything else
The colour and the clarity point to the cause, and the cause decides the cure. Look in daylight, from the poolside, before anything is added.
| What you see | Most likely cause | First step |
|---|---|---|
| Clear water with a green tint | Algae starting, or dissolved metals | No swimming; have it tested |
| Green and murky, floor hard to see | An established algae bloom | Keep everyone out and call |
| Green or dark patches on walls and steps | Algae growing on the surface | Brush if you can, then call |
| Milky white or grey haze | Filter not coping, or water out of balance | Check pump and filter; test |
| Brown or grey haze after wind | Fine dust in suspension | Skim, run the filter, then test |
| Dull water after a busy weekend | Sanitiser used up by heavy use | No swimming; test |
The one check that decides whether anyone swims
Stand at the edge of the deep end and look for the main drain on the floor. If you cannot see it clearly, the pool is closed. This is not about appearance. A swimmer in difficulty at the bottom of a cloudy pool cannot be seen from the side, and water that has lost its clarity has usually lost its sanitiser as well. Keep to the rule on the days when the water is only slightly hazy, the weather is hot and the children are asking.
Why pool water turns green
Algae spores arrive in every pool, all the time. Wind and dust carry them, and so do leaves, rain, swimwear and pool toys. In water with enough working sanitiser they are killed as fast as they arrive. They take hold when the sanitiser drops, and in warm water they multiply quickly. A pool that was clear at the weekend can be green by the middle of the week. These are the usual ways the sanitiser comes to fail.
- A missed visit or a missed dose, most often during summer travel.
- A pump that stopped: a tripped breaker, a timer knocked out by a power cut, a basket so full that the flow failed.
- Sun and heat, which use up chlorine faster than the routine allowed for.
- A pH that has drifted high, so that the chlorine is present but sluggish.
- Too much stabiliser, built up over several seasons, which holds the chlorine back in the same way.
- A dirty or worn filter, and still corners where the water barely moves.
- Food for the algae: dust, rotting leaves, and fertiliser or soil washed in from the garden.
- Heavy use, which can consume the sanitiser in an afternoon.
Why the cause matters as much as the cure
Usually it is two or three of these together. That is why a recovery starts with questions about the last few weeks, and why the water is tested before it is treated. Killing the algae without finding out why the sanitiser failed gives you a clear pool for a fortnight, and then the same phone call.
Green but clear: metals, not algae
Sometimes the water turns green or blue-green and stays perfectly clear, often within hours of chlorine being added. That is not algae. It is dissolved metal, most often copper, reacting with the chlorine. Copper can come from some algae treatments, from the fill water, or from metal parts of the equipment that acidic water has slowly eaten into. More chlorine does not help. The water needs a test for metals and a treatment made for them, and the cause has to be corrected so that the colour does not return. Brown or rust-coloured water points to iron in the same way.
Yellow dust and black spots
Two kinds of growth behave differently from ordinary green algae. A yellow or mustard-coloured dust on the shaded walls, which brushes away easily and is back within days, is a form of algae that shrugs off normal sanitiser levels and clings to brushes, toys and swimwear, so those have to be cleaned as well. Small black or dark blue-green spots that do not brush off have rooted in the grout or plaster under a protective layer. Both need a technician, firm brushing and patience. Neither gives way to a single treatment.
Why pool water turns cloudy
Cloudy water has more possible causes than green water, and they overlap. Each one is put right differently, which is why guessing wastes time.
The filter is not removing what it should
This is the commonest cause. The filter is clogged and needs backwashing or cleaning, the pump is running too few hours for the season, or the baskets are full and the flow is weak. Older filters develop faults of their own. Sand that has been in service for years packs down and forms channels, and lets fine dirt pass straight through. A cartridge wears thin. A cracked part inside a sand filter sends sand back into the pool, where it shows as a small pile under the return jets. In those cases cleaning the filter again changes nothing, and the answer is new sand, a new cartridge or a repair.
The water is out of balance
When the pH, the alkalinity or the calcium level is too high, minerals come out of solution as a fine white haze. It is the same material that forms scale on the tiles. An Abu Dhabi summer pushes pools this way, because evaporation concentrates the minerals and each top-up adds more. The haze does not filter out easily, and it returns until the balance is corrected. Some products also cloud the water for a few hours after they are added. That kind clears by itself with the pump running.
The sanitiser is low
Before a pool turns green it often turns dull. Bacteria and the first algae multiply in water with too little working chlorine, and the result is a flat, slightly milky look with no colour in it yet. This is the cloudiness to take most seriously. It is the kind that is unsafe to swim in, and the kind that becomes a green pool within days.
Fine dust after wind
The finest dust a windy day brings is smaller than most filters catch on a single pass. It hangs in the water as a brown or grey haze while the heavier sand sinks to the floor. A dust haze in an otherwise healthy pool is the least worrying kind, although it still loads the filter and uses up sanitiser. The order of work for the pool and for the rest of the house is in cleaning a villa after a sandstorm.
What to do in the first hour
These steps are safe for an owner, and they make the technician's work quicker. None of them involves chemicals.
- Close the pool. Nobody swims, and pets are kept from drinking the water.
- Check that the pump is running and that water is coming strongly from the return jets. If the pump is silent, look at the timer. If a breaker has tripped, do not keep resetting it.
- Check the water level. If it is below the skimmer opening, top it up so that the pump is not drawing air.
- Net out leaves and debris from the surface and, as far as you can reach, from the floor. Rotting debris uses up whatever sanitiser goes in next.
- Empty the skimmer baskets.
- If you have a pool brush that suits the finish, brush the walls, steps and floor. Algae that has been loosened is far easier to kill than algae left as a film.
- Leave the pump running day and night until the pool has been seen.
- Take photos in daylight: the water from the shallow end, the waterline, any patches, the filter gauge and the equipment. Write down when the pool was last serviced and anything added since.
- Book a visit. Green or cloudy water is a reason to book straight away, not to wait for the next service day.
What not to do
Most of the damage in a pool recovery is done in the first hour, by someone trying to help.
- Do not pour in chlorine or anything else on a guess. Without a test you do not know whether the pH will let it work, and a second product added on top of the first is how accidents happen.
- Never mix pool chemicals with each other or with household cleaners. If a product has to be diluted, it is added to water, never water to it.
- Do not drain the pool.
- Do not switch the pump off to save electricity while the water is bad. Still, warm, untreated water is the worst case.
- Do not allow a quick swim because the water is only slightly cloudy.
How a green pool is put right
The treatment belongs to a pool professional. It uses sanitiser at a strength well above normal, and the amounts depend on the test results and the product. The sequence is worth knowing all the same, so that you can follow what is being done and why it takes the time it does.
- Test first. The pH is corrected before the main treatment, because sanitiser added to water with the wrong pH is largely wasted.
- Remove the debris. Leaves and sludge on the floor are netted or vacuumed out, so that the treatment is spent on the algae and not on the rubbish.
- Brush every surface, hard: walls, floor, steps, corners, behind the ladders and under the lip of the coping.
- Clean or backwash the filter and confirm the circulation, so that the pool starts with an empty filter and full flow.
- Raise the sanitiser to a level that kills algae, following the product label and the test. This is the step often called a shock treatment.
- Run the pump without a break. The treated water has to reach every part of the pool, and the filter has to start catching the dead algae.
- Brush again over the following days, so that algae sheltering on the surfaces is pushed into the treated water.
- Clean the filter repeatedly. At this stage it loads up in hours, and if it is not cleaned the dead algae goes round and round.
- Vacuum the settled dead algae, often straight to waste so that it bypasses the filter. The pool is topped up afterwards.
- Retest and rebalance. The pool reopens only when the water is clear to the floor and the readings are back in range.
The colours along the way
A recovering pool does not go from green to blue. It goes from green to a cloudy grey-green, then to a milky pale blue, then clear. The cloudy stage is dead algae in suspension, and it is a sign the treatment has worked. It worries owners more than the green did, and it is the stage where the work is mostly filtering, vacuuming and filter cleaning. A fine-particle treatment is sometimes used to help. A clarifier gathers small particles into pieces the filter can hold, and a flocculant sinks them to the floor to be vacuumed out. Which one, and whether either is needed, is the technician's call.
Why draining is rarely the answer
It is tempting to empty a green pool and start again. In most cases that is the wrong choice. The algae is on the walls, in the filter and in the pipework as well as in the water, so a refill on its own solves little. An empty pool is at risk in a way a full one is not: the shell can crack or lift without the weight of the water, and a finish left dry under the summer sun can be damaged. And a pool's worth of water is a great deal to throw away.
Replacing part of the water is sometimes right, for instance where stabiliser or dissolved minerals have built up too far to correct, or after years of neglect. That decision follows a full test, and it is made by the professional.
How a cloudy pool is put right
Cloudy water without algae is treated by finding which of the causes applies. The filter is cleaned, and the pump is run for longer or without a break. The water is tested, and whatever is out of range is corrected. Settled dust is vacuumed. If the haze remains, a clarifier or a flocculant may be used. If the filter itself is worn, its sand or cartridge is replaced or the fault repaired, because no chemistry makes up for a filter that lets the dirt through.
How long it takes, and what decides it
There is no honest single figure. Our service page puts the reset of a neglected pool at several hours of work, sometimes spread across more than one visit, because the water needs time to respond to treatment between cleanings. A light case caught early often clears within a few days. A pool left through a summer holiday commonly takes a week or more, with repeat visits. Ask for an estimate after the first visit, when the test results and the state of the filter are known, and expect it to be revised if the water responds slowly.
- How far it has gone. A green tint with the floor still visible is the quickest. Dark green water over a layer of leaves is the slowest.
- The filter. A small or tired filter clears a pool slowly, however good the treatment.
- Whether the pump can run without a break, and whether someone can clean the filter between visits.
- The stabiliser level. Very high stabiliser makes any treatment less effective.
- The water temperature. In summer, algae grows back fast if the treatment falls short.
When the water should be tested by a professional
Test strips from a pool shop give a rough reading of sanitiser and pH. They are useful between visits, they spoil quickly if they are stored in heat, and they do not show the things that most often lie behind a pool that keeps going wrong. A professional test adds total alkalinity, calcium hardness, stabiliser and the difference between working chlorine and used-up chlorine. Where needed it also covers metals, the salt level and the nutrients algae feed on. Have the water tested professionally in any of these cases.
- It is green, at any depth of colour.
- It is cloudy, and a day or two of continuous filtering has not cleared it.
- The problem has come back after being treated.
- Swimmers report stinging eyes, itchy skin or a strong chlorine smell.
- The water is clear but an odd colour, or stains are appearing on the finish.
- The pool has been closed up or unused for weeks.
- You have just moved into a villa and do not know the pool's history.
- A large amount of water has been replaced, or a dust storm has passed.
- Someone has been sick in the water, or a nappy has leaked. That is a hygiene problem, not a clarity problem: everyone out, and call.
Safety while the pool is being treated
A pool under treatment holds far more sanitiser than a pool in normal use. It can irritate skin and eyes and bleach swimwear, and a pet that drinks from it can be made ill. Keep swimmers and animals out until the technician says the water is ready, or until the waiting time on the product label has passed and the water is clear. If the two differ, take the longer.
Chemical handling follows the same rules as always, and a recovery is when people are most tempted to break them. Never mix products. Always add a chemical to water, and never water to a chemical. Use one product at a time and let it circulate. Store what is left closed, dry, apart from other products and out of the sun, where children cannot reach it. For target readings, follow the product label and the pool professional's test results.
Murky water is a hazard in itself. A child who falls into a green pool cannot be seen from the side. While the water is bad, the barrier and the gate matter more than at any other time. Keep the gate latched and the doors from the house locked, and take toys away from the edge. Supervision does not relax because nobody is meant to be swimming.
Stopping it coming back
A recovered pool has been given a clean start, not immunity. Whatever let the sanitiser fall will do it again unless something changes. Ask the technician what the cause was, and deal with that.
| Cause found | What changes |
|---|---|
| Missed visits or summer travel | Keep the service running while away, and arrange access |
| Pump stopped or timer reset | A daily look at the pool; the fault repaired |
| Filter worn or overloaded | New sand or cartridge; cleaning by the gauge |
| pH or stabiliser too high | Regular full tests, not strips alone |
| Leaves, clippings or fertiliser | Planting trimmed back; sprinklers turned away |
| Dust after windy days | Skimming and filter cleaning sooner after wind |
The routine, the garden and the paving
The weekly routine that keeps a pool out of trouble, and how the work divides between an owner and a technician, is set out in villa pool care in an Abu Dhabi summer. If trees or sprinklers are the source, a garden maintenance visit can cut back what overhangs the water. Green or dark growth on the paving round the pool is a job for pressure washing, where the surface allows the treatment. It should not be hosed into the pool.
If the pool is on a service agreement with any company, read what it says about recovery. Whether rescuing a green pool is included or charged as a separate job is one of the questions to settle before signing, and it is covered in annual maintenance contract or pay per visit.
Booking a recovery with us
A neglected pool that needs a reset is quoted differently from routine upkeep, so the more we know before the visit, the more accurate the quote. The price depends on the pool's size, how far the water has gone, the state of the filter and pump, and how much dosing is needed to bring the water back into range. We do not publish a price for pool work. These are the things to send.
- Photos in daylight: the whole pool, the water close up, the waterline and any patches.
- A photo of the filter, its gauge and the pump.
- The pool's rough length, width and depth, and whether it is a chlorine or a salt pool.
- How long the water has been like this, and how long the pool was out of use.
- When it was last serviced, and anything added since.
- Whether the pump is running.
The quote, the payment and the day
Book the service on the website or in the IHR Dream app and say in the description that the water has turned. Then email the photos to info@ihrdreamcleaning.com with your name and booking details, so that they are matched to the right job. Where the pool has to be seen, the inspection is free in every area we serve. Once the price is confirmed you pay by card from My bookings on this website, and jobs of AED 1,000 or more take a 30% advance by that link.
A one-off reset does not commit you to anything further. A regular schedule can follow it if you want one, and staying on a schedule is the most effective way of keeping algae and staining from building up again.
On the day, the technician needs access to the pool and the plant room, power to the pump and someone to open the gate. Before leaving, the technician shows you the pool, the water test result and the pump and filter settings. If a second visit is needed, ask what to do in between. Usually it is to leave the pump running and keep everyone out.
Common questions
Is it safe to swim if the water is only slightly cloudy?
Not until it has been tested. Slight cloudiness is often the stage at which the sanitiser has just failed, which is when the water is least safe and looks least alarming. Use the drain check. If the main drain is not sharp and clear from the poolside, nobody swims. If it is, a test still comes before the swim.
Can I just add more chlorine?
Sometimes that is part of the cure. On its own, without a test, it often fails. If the pH is high, most of what you add does little. If the stabiliser is very high, the same. If the green comes from metals, chlorine makes the colour worse. And if the filter is not working, the dead algae simply stays in the water. The treatment is chosen from the test result, which is why the test comes first.
The chlorine reading was fine. Why did the pool still go green?
There are three usual reasons. The reading may have shown total chlorine, which includes the used-up part, and not the working part. The pH or the stabiliser may have been high enough to hold the chlorine back. Or the strip may have been old, or kept in a hot plant room, which makes it read wrongly. A full professional test separates these.
The green has gone but the water is still cloudy. Has the treatment failed?
No. That is dead algae, and clearing it is the slow part: continuous filtering, repeated filter cleaning and vacuuming. If the haze has not shifted after several days of that, the filter itself is the suspect.
Will green water stain the pool?
It can if it is left. Algae on grout and plaster leaves shadows, leaves on the floor leave brown marks, and black spot roots itself in. Metals stain as well. Most marks from a short episode come out with brushing once the water is balanced. A pool left green for a season can keep some of them, which is one more reason to act in the first week.
The pool went green while we were away. What should we do first?
Keep everyone out, check that the pump is running and the level is up, clear the debris, take the photos and book. Do not start with chemicals from the store room. A house that has been closed for weeks brings a list of other jobs, and they are set out in cleaning a home after summer travel.
Act in the first week
A pool that has just lost its clarity is a short job. The same pool three weeks later is a long one, with more visits, more water lost to vacuuming and backwashing, and a greater chance of marks that stay. Close the pool, do the safe first steps, take the photos and get the water tested.
What a pool visit covers, and what affects its price, is on the pool cleaning and maintenance page. We are open every day from 8 AM – 8 PM. When you book, say that the water has turned and send the photos, and the scope and the price are confirmed with you before anyone starts.
