Cloudy pool water or cloudy spa? Take a look at its causes, and how to fix it
As (new and old) pool owners, we’ve all had the problem of cloudy pool water at one time or another, something we definitely don’t want to have.
Not only it is not pretty to look at, but a cloudy pool can also mean that your water is unsafe and can pose a risk to swimmers. Let’s take a look at what makes pool water cloudy and how to clear it.
What makes pool water cloudy and how to fix it
The most common causes of cloudy water are improperly balanced water chemistry, insufficient water filtration, environmental conditions, and the addition of granular or powder chemicals.
1. Improperly Balanced Water Chemistry
2. Insufficient Water Filtration
3. Environmental Factors
4. Addition of Chemicals
There are several other chemicals that can result in cloudy water, but these are the three most commonly observed.
Improperly Balanced Water Chemistry
When free chlorine levels dip below the recommended amount, microorganisms such as algae and bacteria can cause water to cloud, turn murky or even turn green.
Some common causes of low free chlorine are dilution due to heavy rainfall, organic contaminants, and low stabilizer (CYA). In some cases, too much CYA can lead to a situation where the pool is green but chlorine is high.
Last but not least, and the easiest of all to fix, is failing to maintain proper chlorine levels.
When the chlorine falls below recommended levels then the water should be shocked until the water is clear again.
In that article, you can find out how many chlorine tablets you need to add to your pool.
pH impacts chlorine’s ability to sanitize. In other words, the levels of chlorine and pH must be balanced to ensure proper water quality.
High pH can also enable calcium to precipitate from solution and cause clouds of calcium carbonate in your water.
pH should be lowered or raised to keep between 7.2 and 7.8 ppm to support effective sanitation and water balance, avoiding eye and skin irritation.
A lot of people ask how to clear a cloudy pool with baking soda, but doing so increases alkalinity and that can make pool water cloudy when combined with shocking.
If the alkalinity is above recommended levels, the pH will bounce. This will allow the precipitation of calcium, thus decreasing chlorine effectiveness.
High levels of calcium can react with high pH to cloud water as noted above, and if left untreated it can also cause scaling. High calcium levels can also cause clouding when water temperatures are above 85°F.
Calcium hardness can be lowered by replacing a portion of your water, assuming you do not have a high level of calcium in your fill water.
Insufficient Water Filtration
Pump Run Time
Your pump running time should work enough each day to filter the debris and fine particles from your water.
On average, typical run times are anywhere from 8 to 12 hours per day depending on the size of your pool (or spa) and your specific equipment. Check here if you don’t know how long to run your pump.
Dirty or Malfunctioning Filter
This is also a common issue and an easy one to fix. There are several types of filters and the one thing in common to all of them is that filters should be cleaned periodically as they need they need maintenance.
Rain is wonderful and helps keep landscapes lush and green, but it can also make your pool (or spa) lush and green. Rain can dilute chlorine, CYA, pH, and can also introduce minerals, sand, mud and other contaminants that reduce water clarity.
Contamination combined with the dilution of chlorine and pH can lower sanitation effectiveness and lead to a green cloudy pool.
Prepare your pool (or spa) prior to rain if possible by balancing your water and increasing your chlorine level. After the rain is gone, run your filter continuously to filter out particles until your water is clear.
If you didn’t raise your chlorine level in advance, balance your water chemistry to proper levels and consider shocking to give your chlorine a boost.
Swimmers and Bathers
Swimmers and pets altogether can introduce a multitude of contaminants in your pool, both organic and inorganic. A few examples are sunscreen, lotions, soaps, food, and waste.
Plan in advance to have shock on hand. Once you are finished with your pool party, balance your water, shock, and run your filter continually until the water is clear.
Once again, you can also use floc or clarifier depending on your specific needs.
Check the skimmer baskets prior to shocking – you never know what you may find. Cupcakes and clothes are some of our favorites finds 🤣 – What’s in your skimmer basket?
Addition of Chemicals
Cloudy pool water after shock has been added in powder or granular form is due to the chemicals not being completely dissolved.
This could be due to multiple reasons such as water temperature, inadequate premixing or simply because it’s an expected event to some extent.
If your water is cloudy after adding dry shock, wait it out and keep your pump running until the water clears.
This typically should occur within a few hours, but depending on various factors such as the quality of the product, circulation, and filtration it can take overnight or longer.
Copper and Iron can also be introduced by your fill water (well water typically contains a lot of metals and minerals). If your water is cloudy after adding algaecide, wait it out and keep your pump running until the water clears.
If your water turns green very shortly after adding algaecide that means that a high dose of chlorine oxidized the copper from the algaecide.
You should avoid high chlorine levels when the level of copper in your water is greater than ~.2ppm. To clear the green tint, you can use a chelating or sequestering agent to bind the copper in solution, or you can use a product that binds the ions and removes them completely from your water.
Phosphate removers can also cause cloudy or hazy water as they bind to phosphates and cause them to fall out of solution and precipitate for removal by filtration.
If your water is cloudy after using phosphate remover, continue to follow the product instructions and wait it out.
Keep a close eye on your filter pressure in the following days damage could occur if the pressure is allowed to get too high. You will likely need to clean your filter to lower the pressure within 24 to 36 hours after treating your water.
How to fix Cloudy Water
Here’s a guide to solve some of the most common causes of cloudy water and what you can do to address them. But you’ll see that sometimes it’s better to see the overall game plan for how to get rid of cloudy pool water, so let’s asess the situation step by step.
Analyze your current situation. What event might have caused your pool water to turn cloudy? Was there rainfall, did you add any chemicals or did you have a party?
- After assessing the situation to get some ideas of what may be causing your issue, check your water chemistry.
- If water is balanced and free chlorine is within range, then clean/brush/filter and wait it out for a bit. Consider floc or a pool clarifier if you need to clear more quickly.
- If water isn’t balanced and/or free chlorine is low then balance water and shock. Clean/brush/filter and wait it out for a bit.
- If you see algae, wait 24 hours after shocking and you can add algaecide, or you can continue to hold water at shock level until algae is gone. Remember to brush daily while eliminating an algae infestation.
- Check that your filtration system is functioning properly. Consider when the last time was that it was cleaned, is the pressure higher than normal, and are there any visible reasons it could be malfunctioning (media is old, filter is dirty or clogged, run time isn’t sufficient etcetera).
- Wait it out for a bit, keep testing your water and look for signs that you are making progress. Take pictures to compare day by day.
Now you can show people how much of a pool pro you are now.
Now you know how to clear up a cloudy pool and what causes cloudy water, so your last task is to keep it clear.
Sutro smart pool monitor can help keep you from having a green cloud over your head and milky pool water by monitoring your chemical levels and helping you keep them in check before they get out of hand. “Wow, your pool is clear” is what we want you to hear!