My parents are away on vacation, and I’m in charge of taking care of their pool. I’ve been busy with summer classes and meeting deadlines at work that I’ve been slacking on cleaning and maintaining the pool. Now, the water is green.

How do I clear a green pool? 

It happens to just about every pool owner at some point: the water turns green. It’s not pretty, and it’s not a fun situation to fix. But it is fixable with a little time, work and the right products.

Pool water turns green for one reason: algae. Algae starts to grow when the pool’s sanitizer levels are too low. The darker the green, the bigger the problem. 

In most cases, the problem can be fixed by shocking the pool and making sure that the water is balanced from here on out.

Before you get started, you’ll need to gather some supplies:

  • Pool vacuum
  • Algae pool brush
  • Test strips
  • Pool shock with 70%+ available chlorine

Start by vacuuming the pool to Waste. Set your filter valve to Waste, and then get to work vacuuming. The goal is to remove as much algae and sediment from the pool as you can. In future, we’d recommend getting a top 10 above/in ground pool automatic pool cleaner for convenience and ease of use. 

We found this next tip from Pool Rescuers tips. What you’ll want to do is use an algae brush to scrub any surface algae may cling to, like the walls, floors and steps of the pool. 

Next, you’ll want to test the water’s pH and alkalinity. If the pH is very high, you’ll wind up with a very cloudy pool. The pool will be cloudy anyway after shocking it, but it will clear up after the algae dies and other solids are filtered out. 

The next step is to shock the pool to kill the algae. You may want to refer to this step by step guide for a more detailed explanation, but we’ll talk about how this works.

Ideally, you want to use a shock that has at least 70% available chlorine – and you’ll want to shock the pool twice. If the water is dark green, you may need to shock the pool three times. 

After shocking the pool, you’ll want to turn on the filter and leave it on until the water is completely clear. Be patient. It will take a few days to kill the algae, filter it all out, and for the water to become clear.

You can use a pool clarifier if you want to speed up the process, but you still want to run the filter for at least 24 hours to remove all of the dead algae and ensure that all of the shock has dissipated. 

Test the water again once it turns clear to make sure that it’s properly balanced. If necessary, add chemicals to balance things out. Keep testing and balancing until you get the water back to a normal state.

To keep the algae from coming back, you want to make sure that you maintain proper sanitizer levels. 

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