Cloudy water is more than an eyesore. It is a sure sign that something is off with your filtration or water chemistry, and it can point to bacteria in the water. This guide covers what makes pool water cloudy, how to clear it and how to keep it from coming back.
Why is my pool water cloudy?
Your pool is cloudy because tiny particles are suspended in the water and reflecting light back, which makes it hard to see the bottom. These particles are nearly impossible to see one by one, but together they have a major impact.
Unlike leaves and other larger debris, these particles cannot be skimmed out or picked up by a pool vacuum. They get into the water in many ways, including the surrounding environment, swimmers and even leftover chemicals at the tail end of their lifespan. Your sanitizer and filter are what normally deal with them. When either one falls behind, the particles build up and the water turns cloudy.
Cloudiness also tends to get worse over time. Without proper care, clear water can go from dull to cloudy to opaque, then teal and eventually swampy and green.
What causes cloudy pool water?
The most common causes of cloudy pool water are poor filtration and sanitizer levels that are too low to keep up. Chemical imbalance, environmental debris, phosphates, heavy rain and heavy swimmer use all add to the problem.
- Poor filtration: a clogged filter, a strained pump or not running the filter long enough
- Low sanitizer: not enough chlorine or other sanitizer to attack germs, bacteria and particles
- Chemical imbalance: pH, total alkalinity or calcium levels that are off
- Too much shock: overusing shock treatments
- Environmental debris: sunlight, heat, pollen, leaves, dirt and bird droppings
- Phosphates: organic material that feeds algae
- Heavy rain: extra water that dilutes chemicals and carries in runoff
- High swimmer traffic: sunscreen, makeup, hair oils, sweat and more
Filtration problems
An efficient filtration system is the most important part of a clean pool, and poor filtration is the main cause of cloudy water. A clogged filter, a strained pump, poor filtration habits or simply not running the filter long enough all leave particles in the water. Without a smooth running system, your water will be cloudy and unsanitary too.
Low sanitizer levels
At its core, cloudy water often comes down to not having the right sanitizer levels. Chlorine and bromine attack germs, bacteria and the particles that cause cloudiness. If chemical treatments are not done regularly, there is nothing left to attack those particles. Anything that reduces the efficiency of your pool chemicals is a big problem.
Chemical imbalance
Pool chemistry works like a row of dominoes. When one level goes, others are quick to follow. Too few chemicals open the door to cloudy water, and so can too many.
- pH: When pH is off, chlorine loses its impact and can become ineffective. High pH makes water less acidic and causes scale to form in the pool and plumbing. Scale hurts your filter and makes sanitizers less effective.
- Total alkalinity: High alkalinity makes pH hard to stabilize, contributes to calcium scaling and reduces the effectiveness of chlorine and other sanitizers.
- Calcium: High calcium creates a flaky buildup that can clog the pump and filter. This is a problem whether you have a cartridge filter or a sand filter.
- Too much shock: Shock can give a quick surface improvement, but overusing it can do the exact opposite and cloud the water.
Environmental debris and contaminants
Your pool’s surroundings take a steady toll on sanitizers. Prolonged direct sunlight and high heat cause water to evaporate and eat away at sanitizer. Bird droppings, dirt, pollen, leaves and other natural debris make sanitizers work harder, spreading them thin until they are no longer effective.
Phosphates and algae
Phosphates are organic materials that occur naturally in pool water. They come from things like pollen, leaves and lawn fertilizers. When phosphate levels are high, they feed algae and help it thrive, and algae will turn your water green and cloudy.
Heavy rain
Any extra water dilutes your chemical levels, and a heavy rain can add a large amount all at once. Rainfall can also carry nitrates, phosphates and other runoff into the pool, throwing off your water balance.
High swimmer traffic
The more people use your pool, the bigger the impact on your water chemistry. Makeup, sunscreen, hair oils, sweat, topical medications and anything else on the body can end up in the water, where it reflects light and makes it hard to see the bottom.
Is cloudy pool water dangerous?
Cloudy water can be a health risk because it may mean the sanitizer is not killing bacteria and other organisms. When chlorine is not working, swimmers can pick up recreational water illnesses (RWIs).
Stepping into cloudy water can lead to skin irritation, swimmer’s ear and other ear infections, eye infections and digestive issues. For commercial pools the stakes are higher, since one negative social media post can send customers to a competitor.
How do you fix a cloudy pool?
To fix a cloudy pool, find the cause first, then treat it. That usually means testing and balancing your water chemistry, cleaning and running the filter and clearing out debris, rather than relying on shock alone.
- Test the water. Check chlorine, pH, total alkalinity and calcium so you know which levels are off.
- Balance the chemistry. Bring each level back into range. Remember that too much of a chemical can cause cloudiness just like too little.
- Use shock carefully. A shock treatment is a good first step to get chemistry back on track, but it is a quick fix and particles will likely remain in the water. Avoid overusing it.
- Clean the filter. Clear any clogs and check that the pump is not strained.
- Run the filter. Run it for a few hours a day to keep water circulating.
- Remove debris. Skim the pool, empty the skimmer basket and brush and vacuum the pool.
The goal is to treat the cause and not just the symptom. If you are not sure what is behind the cloudiness, a professional water test and a custom treatment plan will get you there faster.
How do you stop cloudy pool water from coming back?
The best way to prevent cloudy water is regular maintenance. Keep your filter clean and running, test and balance your chemicals on a schedule and check them again after heat waves, heavy rain or heavy use.
- Clean the filter regularly and run it a few hours every day.
- Keep the pool and skimmer basket clear of leaves and other debris.
- Test chlorine, pH, total alkalinity and calcium regularly.
- Recheck your levels after heavy rain, high heat or a busy pool day.
- Keep lawn fertilizers and other runoff away from the water to limit phosphates.
- Do not skip care in the off season. Throwing on a cover and forgetting the pool only lets problems grow.
All it takes is one missed cleaning or chemical treatment to send a pool into a downward spiral. If you go away on vacation without a plan, you may come back to a swamp.
When should you call a pool professional?
Call a pool professional when your pool stays cloudy after you have balanced the chemicals and cleaned the filter, or when you cannot pin down the cause. With so many possible reasons for murky water, the first step is finding exactly what the issue is.
A trained technician can test the water, build a treatment plan that balances chlorine, pH, total alkalinity and calcium and inspect harder to reach areas like the pump and filter. Professional care also makes sense if you manage a commercial pool, are heading out of town or simply do not have time to fit pool care into your routine.
Frequently Asked Questions
Is it safe to swim in a cloudy pool?
It is best to avoid it. Cloudy water can mean the sanitizer is not working, which allows bacteria to grow. Swimming in it can lead to skin irritation, ear and eye infections and digestive issues.
Will shocking the pool clear cloudy water?
Shock can help as a first step, but it rarely solves the problem alone. Particles can stay suspended in the water, and overusing shock can make cloudiness worse. Balance your chemistry and clean your filter as well.
Can too many chemicals make a pool cloudy?
Yes. Too many chemicals can cloud a pool just like too few. High pH, high total alkalinity, high calcium and too much shock can all lead to cloudy water.
Can a dirty filter make my pool cloudy?
Yes. Poor filtration is the main cause of cloudy pools. A clogged filter or strained pump cannot remove the tiny particles that make water look hazy, so clean your filter regularly and run it a few hours each day.
Why is my pool cloudy after rain?
Heavy rain adds water that dilutes your chemicals, and it can wash nitrates, phosphates and other runoff into the pool. Test and rebalance your water after a big storm.
If you would rather spend your time swimming than testing, Puddle can help. Our CPO certified technicians clean your pool, test and balance the water and send you an E-Report with photos and readings after every visit, so you always know how your pool is doing. Request a free quote and we will get back to you within 24 hours.
