How to Clean Cloudy & Green Pool Water – Causes & Remedies

If your swimming pool has turned cloudy, milky or green. this is usually caused by:

  1. Improper levels of chlorine
  2. Imbalanced pH and alkalinity
  3. Very High Calcium hardness levels
  4. Faulty or clogged filter
  5. Early stages of Algae
  6. Ammonia
  7. Debris

Poor circulation, poor filtration and improper water balance can lead to cloudy pool water. Test the water frequently and correct as needed to help keep the water clear. Shock or a water clarifier can help do the trick. Follow the directions on the product label.

What Causes Cloudy Pool Water?

Low Chlorine Levels

The first and most common cause of cloudy pool water is low free Chlorine (FC) Level. Test your free or combined chlorine; if you have FC below 3 ppm or combined chlorine (CC) above 0.5ppm, you will need to shock your pool immediately to fix the cloudiness.

Low Filtration Efficiency

A clogged filter, dying pump or simply not running your filtration system for at least eight hours a day can cause cloudy pool water. If all of your water isn’t being run through a fully functioning clean filter, it can retain debris, leaving you with cloudy water in your pool.

Scaling, Pitting and Clogging

You’ll face myriad problems if your water chemistry is out of whack. High pH means your water is less acidic than it should be. The soft water tends to form scale on pool surfaces and inside the plumbing while making it more difficult for your filter to work. This can cause filtration problems, bacteria growth and cloudiness.

High Bacteria Levels

Chlorine or (bromine) servers a vital role in keeping your pool water clear and healthy. The dangerous aspects of a lack of cleaner – whatever the cause – include bacteria growth and increased stress on your filter leading to cloudiness in your pool water.

Your Pool’s Circulatory System

Problems with your pool’s circulation system are a leading cause of cloudy, hazardous pool water. It’s mostly preventable by keeping the circulation system healthy.

Too Much Calcium

How hard the water in the pool is can influence whether it’s crystal clear or murky. Monitor your pool after rainfall. If the water looks cloudy, test the chlorine, pH and other chemical levels with a test kit, then adjust as needed.

Environmental Effects

If it’s nothing to do with your chemicals or your filter, then the only reasonable explanation left is that it was caused by the surrounding environment.

Here are some of the likely environmental causes

  • Leaves & small debris – while leaves will be easy enough to be removed before they dirty up your water, it’s really the build-up of smaller dust particles that can get you into trouble.
  • Insects & small animals – they will always find their way into your pool eventually, but the biggest things to keep an eye out for is droppings, particularly bird poop.
  • Surface & runoff – Heavy rain can cause water to accumulate on the ground, in some cases making it’s way to your pool bringing plenty of other nasty things with it.

How to Clean Green Pool Water – 3 Fixes

After knowing how unpleasant a cloudy pool can be, are you ready to bring your pool back to its previous glory? It will take a little hard work and maintenance but it’s worth it.

If Caused by Environmental Effects

To fix and prevent cloudy water due to environmental effects, follow all of the best practices below:

  • You can use nets to remove visible particles. You can also use a pool clarifier to clear up the water when cloudiness persists. Use a pool flocculant and vacuum the pool to do away with fine particles than cannot be removed by leaf net or clarifier.
  • To remove algae, scrub and clean the pool using a large leaf net and vacuum, follow by a pool shock to get rid of any remaining algae. Finally, control the amounts of pH, chlorine, TA, phosphate and other pool sanitizers to prevent algae growth.
  • If your pool is in direct sunlight, consider using a chlorine stabilizer (CYA) and a pool cover when not using the pool.
  • If rain has diluted and reduced the chlorine free levels, then test the chemicals, paying close attention to the chlorine levels and adjust them as appropriate.

If Caused by Pool Filtration and Circulation Systems

A pool water-circulation system can also be a big problem. If your water cannot circulate properly, it will become stagnant and cloudy. To fix this problem:

  • Ensure that the return fittings (eyeball fittings) are turned to point down, which enables the water at the bottom of the pool to circulate properly.
  • Make sure you are using the right pump size to adequately clean the water.
  • Make sure the filtration system is running long enough. A filter should run 24/7 for the water to remain clean all the time. However for home pools that are not busy, at least 8-10 hours a day might suffice.
  • Remove particles that may be blocking your filter.
  • Ensure that you regularly clean, backwash or replace the DE and cartridge filter medium as appropriate. Cartridge filters usually last 2000 hours and should be replaced every 1-2 years depending on the usage.

If Caused by Chlorine Imbalance

If you have an outdoor pool, you can use a chlorine stabilizer such as Cyanuric acid, to prevent chlorine depletion as a result of direct UV light.

Remember that Cyanuric acid is very strong, and if it exceeds the recommended levels, free chlorine will disappear and the water will turn cloudy causing a high risk of algae development.

Final Note

We hope our expert advise at The Pool Support has helped you with your problem. Now you know what causes cloudy pool water and how you can clean it back to the original state. Take action immediately before matters go out of hand. If this process is to technical for you, hire a pool expert.