How to Clear a Green Pool  

by Pool Builders on 03-13-2013 in Articles

One thing that I have heard over the last few years is people that are having a VERY hard time clearing up their green pool water. This is due to one big factor that was not such a factor years ago: Computer Water Testing. Computer water testing is designed to accurately test your water for the chemicals that you may need and give you the proper amount of the chemicals when needed to raise these levels, however, it does not do a good job of diagnosing the amount of chemicals required to clear up a green pool. I have heard where customers go to and from the pool store every week testing their water and treating the green water and not having any positive results. It is because this: the computer testing is giving you a solution to the green water that is not strong enough to resolve the issue.

Keep in mind that chlorine is a toxic chemical and uses O2 to burn the bacteria out of the water. If this chemical is abused, then harmful damage may occur to the pools liner, the pools components, and if you are in the chemically abused pool, then you will be harmed (burning eyes and irritated skin). With this being said, keep in mind that what I am about to tell you needs to be done just to clear a green pool and not be abused on a day to day basis.

So here is how you clear up a green pool: Algae has a chemical within it called chlorophyll which causes the green coloring. Algae also reproduces very quickly. So to remove the algae from the water, you must overtake the amount of algae in the pool with granular chlorine (shock). I explain this to my customers like this; if your house was on fire, you would not put the fire out in the kitchen and then wake up the next morning to put out the fire in the master bedroom. The fire would spread overnight and all the work you did in the kitchen would have been for nothing. This is what these computer testing stations are having people do. They have you put a small amount of chlorine in the water and then wake up the next day to put in more, but the algae has recovered by then and has reproduced more algae. The key to getting rid of the algae is to shock the pool so heavily that the amount of chlorine in the water overtakes the amount of algae in the water in ONE SHOT. Five pounds of chlorine at one time is way more effective for clearing up a green pool than 1 pound of chlorine a day over five days. So to clear up a green pool, you must heavily shock the water at ONE TIME. I tell my customers to triple shock the pool at one time. For instance,if you normally shock with 2 lbs. of chlorine once a week in a clear pool, then shock the green water with 6 lbs. of chlorine at ONE time and leave the pump running for 24 hours until the pool has cleared.

The clearing of the pool will more than likely follow these steps:

Backwash the filter to make sure that your pump and filter system will be performing at top capacity.

1. Shock the pool with a heavy amount of chlorine (3 times your normal amount) and run your pump 24 hours a day until the pool clears up.

2. You will wake up the next day and the water will not be green, it will be cloudy. This is good. This means that all the algae has been killed and the chlorophyll has been burnt out of the algae, yet the algae shell is still in the water causing the water to look cloudy.

3. Let the pump run for the next day or so for 24 hours and the water will gradually clear up as the chlorine dissolves the algae's shell.

Stay out of the pool for these few days as your chlorine level will be high and can be harmful to your body.

4. Keep in mind that the process of clearing up a green pool can take 3 or 4 days so be patient and the best strategy is to keep the water from turning green in the future.

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