How to Fix Cloudy Pool Water

Water should remain clean and transparent, no matter if it’s in the pool or a spa. When this changes, and it becomes cloudy and opaque, you know there’s something wrong with it. This problem has several causes, some linked directly to the water, while others are caused by external factors. But regardless of which of them is the core of your problem, the good news is that it has solutions.


For an efficient way to revert opaque water to its transparent counterpart, you shouldn’t just treat the effects, but also be aware of what causes it. By knowing what caused the cloudy-effect, you’ll be able to prevent it from happening again in the future, thus helping you save money and time, in return. There are five main elements which can be classified into three categories:

Faulty water chemicals:
Unbalanced levels of chlorine
Faulty alkalinity and pH levels
Deposits of calcium
Faulty equipment:
Filter and pump
External factors:
Environment (rainwater, bird drops, leaves, bugs, sun, number of swimmers)


Before you decide to blindly jump in the problem by pouring large quantities of chlorine into the water and hope it will solve the problem, make sure you test the water first. There are several test kits available at any pool store, so make sure you acquire a detailed one, so you’ll cover more ground.

  • Chlorine – as soon as its level becomes imbalanced, either by being too much of it in the water or simply by not being enough of it present in your pool, the water will start losing its transparency. The chlorine is an important component that is tasked with protecting the water against bacteria and pathogens eliminating them before they could become a health danger. To keep it balanced, its level should be anywhere between 2 ppm and 4 ppm.
  • Alkalinity and pH – although pH is not a direct source of cloudiness, it does influence the chemical interaction between the other components. A high level of pH can create calcium deposits, whereas a low pH level heightens the consumption of chlorine, leading to an insufficient sanitization. An ideal pH level should be anywhere from 7.4 to 7.8, with an excellent concentration at 7.6.

    Also, keep an eye on the alkalinity level, as high alkalinity (also known as total alkalinity) will lead to pH and calcium buildups. To prevent this you can try to use muriatic acid to aerate the water, and in turn, lower the alkalinity levels. However, be careful of how much you use, since the recommended level of alkalinity should be situated between 80 ppm to 120 ppm, or, if your pool is larger, up to 140 ppm.
  • Calcium deposits – highly connected to pH and alkalinity levels, calcium hardness should always stay 0, since as soon as it’s value changes, positively or negatively, it will have an impact on the water. When it goes beyond 0, calcium carbonate will start to form and flakes will appear in the water. If it goes below 0, the water will become acidic and will affect not only the lining but also the pool equipment. Once the damage is done, it cannot be reversed, therefore it is recommended to test for calcium hardness monthly. Its levels should be constant, between 200 ppm and 400 ppm.


Once you’ve ensured the water chemicals are in perfect shape, it’s time to get to the next step, and that is to check and address any issues that might appear with your filter and your pump. You should run your filter and skimmer anywhere from 8 to 10 hours daily, so it could take care of any debris, as well as smaller contaminants that might end up in the water. If you plan on using your pool daily, the filters should run 24/7 to ensure the right amount of cleanness.

Depending on what type of filter you have, ensure its maintenance is always performed regularly. Backwash it and clean it up regularly, and, if the need arises, you can even change the cartridges, the diatomaceous earth, or sand, accordingly. Even more, check if the fittings are connected correctly and if the gaskets are still in top shape. Don’t overlook the drains. By opening them up, you’ll help the filtration system reach the entire pool, removing even those particles that are situated at the bottom of the pool.

The pump also is highly important for the clarity of the water. A strong enough pump will keep the circulatory system always functioning at its best capacity. Ensure the pump you employ is strong enough to cater to your pool’s size. Also, make sure it is compatible with the filtration system since a too-powerful pump will overwork the filter, resulting in a faulty outcome.

Vacuum the pool often. By employing the help of automatic robots, they won’t overwork the pool’s system, as the media will be contained inside the vacuum, thus prolonging the filter’s and pump’s lifespan.

External Factors

If the water chemistry is balanced, and if the pool’s system is not at fault for the cloudy water, then the surrounding environment is also a potential cause.

  • Small leaves – while you might be tempted to neglect those small leaves that are blown away and end up in your pool, with time they will decompose and will affect the water. So, use a pool rake and remove them as soon as you spot them.
  • Insects and animals – insects will, inevitably, end up in your pool, and so will small animals. However, while they might be unpleasant to remove, the main problem is the bird droppings. If possible, they should be removed instantly from the water, as their acidic nature will negatively affect the water.
  • Rain and sun – you might think that rainwater is clean, and therefore it wouldn’t negatively impact the pool water, right? Wrong. Rainwater, especially in large quantities, can bring toxic chemicals into the basin. Additionally, depending on where your pool is situated, extensive sun exposure will make chlorine to deplete faster, therefore lowering the overall sanitization levels.
  • Swimmers – the more swimmers in the pool, the faster will it get dirty, as cosmetics like sun cream, deodorants, and hair products will negatively impact the water.

Final Thoughts

To sum up, to preserve the water clear and transparent, you should keep a regular maintenance period, for both water and equipment. Additionally, you should test the water as often as possible, and balance the chemicals accordingly. Run the skimmer every day, and vacuum it often to ensure that all debris is taken care of accordingly.


  1. Marcus says:

    Should I use a pool clarifier even if I haven’t had issues with cloudy pool water yet?

    • Carl Hudgens says:

      If you don’t have cloudy pool water, you can still use a pool clarifier to prevent this issue from appearing. It won’t endanger the quality of the water, so there’s no need to worry because it’s a good maintenance routine to take up.

  2. Janet says:

    As I know some disinfectants used for swimming pool water disinfection must meet certain demands because they can be irritating to swimmers. What can you tell me about pool clarifiers?

    • Becky Eddinson says:

      A pool clarifier is not a disinfectant that can affect your skin. It is a substance that acts as a coagulant and makes cloudy pools easier to fix.

  3. Alma says:

    Does a Flocculant remove black algae?

    • Becky Eddinson says:

      If you want to remove back algae from your pool, you need more treatments. This is a great solution for fixing cloudy. It has fast results in sending all the tiny particles to the bottom of the pool. However, it won’t help you get rid of black algae.

  4. Maxwell says:

    How much chlorine should I add to my pool?

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