Thankfully, for the 4 most common causes of cloudy pool water, there are also straightforward solutions.

However, all of these problems can potentially pose a health and safety risk for anyone using the pool. So if you notice cloudy pool water, it’s best to avoid swimming until you’re able to test the water and fix whatever is causing the problem.

The most common cause of cloudy water is a low level of free chlorine. This might sound backward, but having a low level of free chlorine can actually mean that your pool smells more strongly of chlorine than it would normally.

Ideally, your free chlorine, or FC levels, should be between 1-3 ppm (parts per million) or combined chlorine above .5ppm, you will need to shock your pool to fix the chlorine problem and clear the water. In saltwater pools, this means shutting down your chlorine generator and manually shocking the pool.
However, in the summer or just after you get your pool up and running again after the winter cold, you could also be dealing with ammonia or algae. This happens because of low FC, and also because your cyanuric acid levels are low. Unfortunately, the best solution here is also to add a lot of chlorine to the pool to clear the ammonia and help your filtration system get back to normal working order.

Other problems, like imbalanced chemicals, a faulty filter, or environmental factors (like having a lot of dust settle in your pool because your next-door neighbor is doing a lot of landscaping or construction) can be solved by testing your pool water and adjusting accordingly.
If the cause of your cloudy water isn’t immediately obvious, running tests on water quality can help you diagnose the problem.

The most common solution for cloudy pool water is either increasing your filtration to make sure you’re getting enough circulation or adding more chlorine to help restore the proper balance of chemicals.

Knowing which solution you need to take can be a more difficult part of the process.

First, you need to test the water. Any pool owner should have a standard pool testing kit that will tell you what level of each chemical your pool needs and will test and tell you if you’re at the right concentration.

You also need to know how big your pool is so you can calculate how much of each chemical you need if you’re making a correction. Over-chlorinating your pool can cause as many issues as under-chlorinating it.

For instance, if you have high pH due to high Total Alkalinity (TA) you can add muriatic acid. Simply reducing your pH could help resolve cloudiness and calcium scaling.

For other problems, like high calcium hardness, the only solution is to partially drain the pool and refill to reduce the overbuildup in the water.
Increasing the pump and filter runtime will also help removing suspended matter that could be attributed to cloudiness. Adding a clarifier will increase its effectiveness.

Most important in all of this is learning to prevent cloudy pool water in the first place. Getting cloudy water almost always means extra time and expense before you’ll be able to use your pool again. These problems are almost entirely preventable with good pool maintenance and monitoring.

Some tricks to prevent cloudy pool water include: