No matter the type, location, or season, a pool can get cloudy. There are a few possible causes for murky water, with the most common causes of a cloudy pool being a low runtime, chemical imbalance, algae, excess debris, and excess calcium. Each problem has a diagnosis and treatment but generally should clear up in a few days with proper attention.
Here are some of the most common causes and how to treat each issue. Your pool will be clear again in no time.
Low Runtime
A pool that is not run for at least 8 hours a day can get cloudy water, especially if it is in regular use. A pool fights off bacteria 24 hours a day, seven days a week, and while the chemicals do the majority of the work, a properly filtered, circulating pool helps ensure that the water and chemicals are mixing properly.
In addition to mixing up the water, a running pool also sucks up debris, such as leaves and twigs, into the skimmer. Chlorine goes to waste when it has to spend all its time working on debris; a running pool gets the debris into the skimmer or filter basket and out of the way so the chlorine can do its job.
Solution
The fix for this cause of cloudy water is fairly obvious: Run your pool more often.
If your pool is cloudy because of low runtime, it is important to backwash your pool at least once per week to make the most of the time the filter system is on.
Chemical Imbalances
One of the more common reasons a pool would be cloudy is a low chlorine level or other chemical imbalance. If not enough chlorine is present, bacteria can grow and turn the pool green or cloudy. The same thing can happen when there is too much alkalinity or too high a pH level.
Testing the pool water easily determines these conditions. If the chlorine is low, add another tablet or some shock to the pool and let it run for two to three days. If the pH is high or low, you can adjust accordingly.
Solution
For all other chemicals, running the pool will take care of the cloudiness over time. Be sure to backwash the filter to make sure it is operating at optimal pressure; this will ensure that your pool will be clear as soon as possible.
Algae
Algae can cause cloudy pool water. Algae come in many types and colors, not just green.
The first step to treating algae (assuming the chlorine level is adequate) is to identify the color. Different colors of algae have corresponding algaecides, which can be added along with a clarifier (if desired) to the pool to clear the water. A clarifier isn’t necessary, but it will speed up the time it takes for the pool to clear up.
Solution
After you’ve added the chemicals, brush down the pool, including the water level, disturb the algae, and remove scum. When left undisturbed, algae can stain your pool surface.
Let the pool run for at least 2 to 3 days and backwash your filter at least once a day until the water has cleared.
The unfortunate thing about algae is that unless it is completely eradicated, it keeps coming back. So if your water does not clear up after a week, you’ll need to take a small container of cloudy pool water to your local pool store. An analysis of the water will determine what kind of algaecide you need.
Excess Debris
Excess debris can negatively impact your water quality by looking unsightly and clogging up your skimmer and pump baskets. Debri also uses up chlorine that would otherwise be used to keep your pool clean.
Solution
Excess debris can be combated in a few ways. First, skim your pool regularly and make sure the skimmer baskets are empty. Second, vacuum your pool and backwash your filter regularly to allow the filter to aid the chlorine in keeping the big stuff out. Lastly, prevent your pool from worsening by frequently testing it to see if the chemicals are low.
Excess Calcium
High calcium can also turn your pool cloudy and create a calcium scale throughout your pool. There are two ways to remove excess calcium from your pool.
Solution
Either add a clarifier and allow the filter to suck up the calcium or drain the pool partially and refill. A clarifier will make the calcium particles clump up, which allows the filter to remove them from the pool more easily, just be sure to backwash to keep them out. Another way would be to drain the pool partially and add fresh water to dilute the calcium, however, be sure to test and balance your pool after.
High pH
PH above 7.8 can also turn the pool cloudy. The best way to determine this is by testing the water.
Solution
If you find the pH is high, you can add a pH minus chemical to bring it back down. After having the water circulate for 24 hours the pool should improve. Be sure to check the alkalinity level of your pool as well because alkalinity helps stabilize the pH level.
Broken DE Filter Screens
This cause only applies to DE filters, which use a white powder to aid in filtration. DE filters have screens inside them that need DE powder periodically added to them to maintain their filtering abilities. When the screens inside rip, they do not catch all the powder added and can release some back into the pool, making it cloudy. Usually, when this happens, you will find some debris under the return fittings in your pool and might even be able to see the pool get cloudy when adding the powder.
Solution
To fix this issue, replace the internal screens of the filter.
Tips for Preventing a Cloudy Pool
- Regularly heck the pool chemistry
- Vacuum your pool weekly
- Backwash your filter system
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Will shock fix a cloudy pool?
Shock could clear a cloudy pool if the cause of the cloudiness is a low level of chlorine. Always test the cloudy water before adding shock to be sure that low chlorine is the cause.
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Can too much chlorine make pool water cloudy?
Yes, too much chlorine can unbalance the pool's chemistry, making the water cloudy. Testing the water will tell you if too much chlorine is clouding the pool.
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Is it safe to swim in a cloudy pool?
Swimming in a cloudy pool would mean swimming in algae or chemically imbalanced pool water, both of which aren’t unsafe but are certainly not ideal. It’s better to be cautious; test the water and treat the problem before swimming.
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How do you clear a cloudy pool fast?
First, check the chemistry to identify the issue, then balance chemicals, backwash the filter, and leave the pool running for 24-48 hours. Backwash the filter every day and leave the pool running until the pool is clean. If desired, add a clarifier to speed up the process after backwashing.