How To Clean Green Pool Water

You are looking forward to using your pool on the weekend after a crazy week at work, but when you get to the pool, the water looks a ghoulish green. Unless it’s St. Patrick’s Day, green water is never a welcome sight. Before you start jumping to conclusions as to how this happened, you should know that green pool water is not unusual.

What Exactly Is Green Pool Water?

Pool water turns green because of a proliferation of green algae. When you don’t use the pool for a while, leaves and other debris keep accumulating in the water. The debris, along with the heat and sunlight, provide ideal conditions for algae, bacteria and other microorganisms to thrive in the water.

Green algae in particular thrive and multiply rapidly in these conditions. These green algal blooms are what turn the pool water green. The darker the color of the water, the higher the level of algal bloom it contains.

You cannot use the pool while the water is green so the first thing you need to do is to get it cleaned out.
So how to clean a green pool? These are the 3 simple steps you need to follow:

1st Step – Scrub And Filter The Pool

Start by checking the filter and make sure it is working properly and not clogged.  Backwash it if necessary and set it to run continuously so that all the algae get filtered out.

Remove all floating leaves and debris using a hand pool cleaner.

Algae tend to cling on to the pool floor and walls. Scrubbing these surfaces thoroughly using a pool brush will dislodge the algae and break them up so the chemicals can work on them faster. Make sure you scrub all corners.

2nd Step – Treat The Pool

First, check the chlorine and pH levels of the pool water. Algal growth is promoted when chlorine levels are too low. If the test indicates that the level of chlorine is less than 1ppm, you will need to shock the water but before that you must ensure that the pH level is balanced.

If the test indicates that the pH level is lower than 7.8, you will need to add sodium carbonate to increase it. If the pH level is higher than 7.8, adding sodium bisulfate will help to decrease it. The amount of chemical required will depend on the level of pH imbalance in the water. Keeping the pump running during this process will help to disperse the chemicals throughout the pool faster.

After you’re done balancing the pH level of the water, it’s time to add pool shock, which will add chlorine to the water, killing the algae and sanitizing the pool so it is ready for you to use.

While one shock treatment may be enough if the pool water was light green, cleaning out a dark green pool may require multiple treatments.

Remember, during all of this time, your filter is running and sucking up all the small debris and algae and it is likely to get clogged after a while. Make sure you stop and clean it often so that the pressure does not build up.

3rd Step – The Final Cleanup

The scrubbing, filtering and shocking will have removed most of the algae but there may still be some dead algae stuck to the pool floor or wall. Using a robotic pool cleaner is the best way to rid of all this remaining debris and dead algae from the pool so your pool water now looks crystal clear.

Check the chemical levels one last time to ensure that all is okay before you jump into the pool.

Tips For Preventing Pool Water From Turning Green

As long as the pool is not being used and is left open to the elements, algae will continue growing and your pool water will turn green eventually. The best way to prevent this is by covering the pool when it is not in use. Other things you can do are to run the filters regularly and do periodic checks of the chlorine and pH levels to ensure that they are within the recommended range.

3 thoughts on “How To Clean Green Pool Water”

  1. Thanks for the tips! Followed this all the way through and it worked like a charm. Much quicker than some of the other methods posted online.

    • Hi Tess. Thanks for your question. This article is really geared around conventional chlorine pools. However, I have just done an article on salt water pool maintenance, which takes you step-by-step through the process. You can find it using the search box at the top of the page.

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