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How to Fix a Green Swimming Pool


Algae, the small microorganism that grows rapidly in warm water, is most likely the cause of your green water. But fear not! Pool algae is very easy to kill and control.

Getting Rid of Algae with Chlorine Shock

Chlorine is a very effective sanitizer for water. When you maintain a swimming pool with 3ppm (parts per million) of chlorine, it will inhibit algae from growing. However, if you let the chlorine drop, even for a day, you might be left with an algae outbreak, which can turn your water green.

The good news is, chlorine can also destroy algae; you just need to boost the levels. The fastest way is to use chlorine pool shock with a main active ingredient of calcium hypochlorite.

How to Shock Your Swimming Pool

To properly and effectively shock your pool, you will need to wait till dusk or night time to do it. Since the chlorine in the shock is unstabilized, the sun will burn it off much faster than regular stabilized chlorine. Shocking during the day will not be as effective.

One pound of shock treats up to 10,000 gallons of pool water. Also, keep the pool filter and pump running for at least 10 hours during and after you shock.

There is a simple formula you’ll need to follow in order to kill the algae effectively. First, you need to determine how much algae is in your water and you can tell by the color.

How to Kill Pool Algae

Light Green or Teal Pool Water:

This means there’s a low amount of algae in your water and you won’t have to use a hefty amount of chlorine shock. In this case, you should double shock your swimming pool water.

To double shock, you will need to add 2 pounds for every 10,000 gallons of water. For instance, if you pool is 20,000 gallons, you will add 4 pounds of shock.

Green or Dark Green Pool Water:

This means there’s a medium amount of algae in your water and you’ll need to triple shock your pool. Triple shocking requires 3 pounds for every 10,000 gallons of pool water.

Black Green Pool Water

This is the worst of the worst. I like to refer to this as The Creature From The Black Lagoon.

You will need to quadruple shock your pool by added 4 pounds of shock to every 10,000 gallons of water. This can be expensive if you have a large swimming pool. Just make sure you follow the same procedures.

Cloudy Blue Water?

The goal with using chlorine shock to kill algae is to get your pool to be a cloudy blue color. Blue or white means the algae has been killed. When algae is dead, it turns a gray color.

Now, you ‘ll need to run your pump and filter continuously until the water is clear. You may want to use a pool clarifier to aid in the water clearing process, this may take some time depending on the size and ability of your filter system.

Source: Swim University

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Includes all the latest information, tips, and expert advice from Zodiac Pool Systems, Inc. on owning the healthiest, safest, most enjoyable pool possible.


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