Cloudy pool water is a common problem that occurs sometimes overnight that makes pool owners concerned about the quality of their water. Aside from the unappealing appearance, many people are more curious to know whether it’s still safe to swim in a cloudy pool.
Pool experts generally recommend you avoid swimming in a cloudy pool. Aside from the obvious lack of visibility, which is a safety risk in itself, cloudiness can also be a sign of low chlorine levels which means that bacteria and viruses are not being eliminated. This can result in contracting bacterial infection and waterborne diseases.
In this article, I will discuss what are the common causes of cloudy pool water, the risks of swimming in a cloudy pool, and how to prevent this problem from occurring in the first place, and how to fix it.
Causes of a cloudy swimming pool
High or low chlorine levels
The most common cause of a cloudy swimming pool is an unsafe chlorine concentration: either too high or too low. The recommended range for the free chlorine in your pool is between 1-3 ppm, though some say upwards of 5 ppm is technically still safe.
Chlorine is the primary sanitizing chemical in your pool and it eliminates harmful bacteria and algae that can spread disease.
If your pool’s chlorine concentration is too high, it will appear opaque. It will also result in common chlorine side effects like dry skin/hair, red eyes, and respiratory problems.
If the chlorine concentration is too low, then the pool will appear cloudy. It will also mean that bacteria and pathogens in the pool are not being eliminated and you are at risk of becoming ill.
There are many factors that can affect your chlorine levels that you need to look out for:
- Rainfall: After a rainy day, your pool will have accumulated a lot of rainwater which can change its pH levels and dilute the chemicals in the pool. All of this will reduce the chemicals’ effectiveness and possibly lead to a cloudy pool.
- Sunshine: The sun’s ultraviolet radiation (UV rays) are able to break down chlorine at a molecular level. If the UV index is high, it can break down most of the chlorine in the pool and leave you with cloudy water.
- Temperature: Bacteria thrive in warm environments, and if the temperature is high enough to increase the water temperature by a few degrees, it can potentially cause such explosive growth that the chlorine has trouble keeping up with it. Plus, the point above also tends to apply on hot days.
- Amount of people in the pool: Each person brings their own bacteria to the pool and an abundance of people in the pool may overwhelm the chlorine’s ability to disinfect the water.
Chemical imbalance in the water
It’s not enough to just dump a bunch of chlorine into the pool and call it a day. Chlorine needs a specific environment in order to work at maximum effectiveness.
To that end, it is recommended that pool owners keep their pool at a pH of 7.4-7.6, and the total alkalinity at 80-120 ppm.
If those numbers are off, then you may find that the chlorine is used up incredibly quickly, or that it is unable to completely disinfect the water, leading to cloudy water.
You should use a water testing kit to ensure the chemical levels are in line. If anything is off – incorrect chlorine levels, pH levels, high calcium or metal content, etc – then the pool will turn cloudy.
Excessive calcium content
The calcium content in your pool is a measure of how hard your water is. Soft or hard water simply refers to the mineral levels in the water.
Soft water can erode your pool walls and floor to get the calcium it needs. Hard water can turn your pool milky and clog filters.
Shocking, or superchlorinating your pool, adds an extremely high concentration of chlorine in your pool for a short period of time, killing all of the bacteria in the pool.
It is often done if you have an algae problem or you suspect the pool water is dirty in some way.
Shocking is very effective, but you are not supposed to use the pool for 12-24 hours after shocking. In the meantime, your pool water can look cloudy.
This kind of cloudiness is normal – it means that the chlorine is still working its magic and killing the bacteria. It will clear up after a day or so.
Clogged up filter
Water circulates through your filter, and any large particles in the water end up getting caught in the filter. The water that returns should be even cleaner than before.
However, over time the filter can get clogged up, and water will not be able to flow through it. This means that the water will start to become stagnant, and the particles that are not being filtered will make your pool look cloudy.
Is it safe to swim in a cloudy pool?
It’s generally not a good idea to swim in a cloudy pool. If you do, you are at risk of the following:
- Low visibility: Not being able to see clearly means collisions are likely to occur. Swimming head first into the wall, into other swimmers, or even just the impact of your head on water if you’re diving head first can cause serious head trauma. Furthermore, parents or lifeguards will have trouble spotting a struggling child.
- Increased risk of infection and disease: Since cloudy water is often a sign of low chlorine levels, then bacteria and pathogens may be running rampant since they are not being eliminated by chlorine.
- Chlorine side effects: Conversely, too much chlorine can also cause cloudy water and its own side effects, such as rashes, coughing, red eyes, respiratory issues, and dry skin/hair.
Plus, if you can’t see anything and it feels like you’re in an underwater sandstorm, then it makes swimming less exciting.
How to keep your pool water clean and clear
So now that we know about the causes of cloudy water and why it’s not safe to swim in it, how can we prevent it from happening in the first place, and how do we fix a pool that is cloudy?
Adjust your chlorine levels
Use a water testing kit and check the chlorine levels.
If it is too low, you need to shock the pool to kill the contaminants in the water and bring the free chlorine levels to where you want them (1-3 ppm).
If the chlorine levels are too high, you can simply wait until the levels drop to a safe range.
Chlorine is the most common cause of a cloudy pool, so this should be the first thing you check.
Clean or change the filter
Inspect your filter regularly, and clean them at least once every six months. Also make sure the filter is set to run all of the pool’s water at least once a day. That typically means running the filter at least 8 hours a day.
If the water starts to look cloudy, consider lengthening the filter’s running time. If you notice that the filter is overly dirty, use a hose to spray it off.
Is your pool still cloudy despite your filter being clean? Then it can be a sign of a chemical imbalance or some other damaged pool equipment.
Perform regular pool maintenance
Sometimes the pool can get cloudy just because of dirt and debris that naturally falls into your pool water.
If your pool is near lots of trees, or runoff from storms is making its way into your pool, then the water is at greater risk of becoming cloudy or murky.
To deal with this problem, you need to clean your pool regularly. Use a skimmer net to scoop out debris along the surface, clean your skimmers, use vacuums and brushes to keep the pool floor and walls clean, etc.
Test your pool water
Pool experts recommend testing your pool water at least 1-2 times a week.
This helps you determine what the water chemistry is like. Is your pool not getting enough chlorine, or too much? Is the water becoming too hard or soft? Is the pH between 7.4-7.6?
Monitoring your pool and adjusting the chemicals as needed is one of the best preventative measures you can do to keep your water from getting cloudy.
Photo Credit: Benny Lin (CC BY-NC 2.0)