Every pool owner has been there at one time or another. You pull back your pool cover to find the water has turned from that beautiful clear blue to a swampy green that does not entice you to go for a swim.

Have no fear. With a little work, you can quickly turn that water from that ugly green to a beautiful crystal clear that is inviting on those warm summer days.

Why Is My Pool Green?

A green pool simply means that algae has temporarily taken over and begun to grow in your pool. Before you start swimming, you will want to treat your pool and get it ready for the warm months ahead.

There are three things you need to clean up your green swimming pool:

  1. Your filter system
  2. The proper chemicals
  3. And you

Although it will take a little work, you can clean your pool in 5 days or less simply by following the proper steps.

Initial Preparation

1. Test the water

Using a chemical test kit, test the chlorine and pH levels of your pool to determine the extent of the problem. If the chlorine levels drop below 1 ppm, it can cause algae to grow in the pool, turning the water green.

2. Balance the Chemistry of the Pool

Based on the test of your pH levels, add either an acid or a base to bring the level to about 7.8. This is higher than the normal range you want when swimming in your pool, but necessary when you are treating it for algae.

To balance the pH, turn on your pump so the chemicals circulate throughout the pool. Correct the pH levels in your pool by adding either a pH decreaser or a pH increaser, depending on which way you need your levels to go.

3. Check Your Filter

Clean out any debris present in your filter such as leaves, sticks and anything else that may be clogging the filter. If necessary, backwash the filter to make sure it is working before you add chemicals to the pool to ensure that it runs 24 hours a day during the cleaning process.

4. Clean the Bottom and Sides of the Pool

While it may be difficult to see the bottom of your pool, use an algae pool brush to scrub the pool before adding chemicals to the water. Algae will cling to the surfaces of your pool but by scrubbing the bottom and the sides, you can break up the algae and remove it from the surfaces so the chemicals work faster.

Shock the Pool

1. Treat the Pool with Pool Shock

Pool shock contains high levels of chlorine that will quickly kill the algae and sanitize the pool. Use a powerful shock with at least 70% available chlorine that can handle both algae and bacteria.

If you have a high amount of algae in your pool, you may have to shock the pool more than once to keep the algae from returning. You may notice the water appearing cloudy or dirty after you add the shock, but as the water runs through your filter it will begin to clear up.

2. Clean Your Filter Often

Once the shock has killed off the algae, you must prevent buildup in your filter by removing it regularly and cleaning it removing the dead algae and other debris that collect in the filter.

The Final Steps

1. Vacuum Up Debris and Dead Algae

Using a pool brush, clean the sides and the bottom of the pool again now that you can see what you are doing. After you have scrubbed the sides and bottom, vacuum up the dead algae and other debris to be sure it is clean.

2. Run the Filter and Monitor Your Pool

After you have shocked your pool and removed all of the debris, your pool should look crystal clear and inviting on those hot days. However, before you jump in, allow your filter to run and check your pool regularly to be sure the algae doesn’t come back. If it does, you may have to repeat the shocking process to get rid of it for good.

3. Check Chemical Levels

Once you have completed all the work and your pool is now algae free, you should recheck your pool to be sure the chemical levels are in proper range before you jump in.

Opening your pool cover to green water may be disappointing, but with just a little bit of hard work and using the proper chemicals, you can quickly remove the algae from the water and return it to the bright, crystal clear colour that everyone loves in a pool.


Need help with your chemical balance? We can help with that too. For a small fee we will come to your pool, test your pool with high tech equipment and we will even add the required chemicals for you. You can book your Bronze Service here.

Leave a Reply