How Long Does It Take To Kill Algae In A Pool?

Algae can form inside your swimming pool’s water quickly, especially after the temperatures outside warm up for the season and your water temp rises above 65 degrees. The quicker you realize algae is alive and well in your water the better. It will make getting rid of the green a quicker and easier process.

So how long does it usually take for algae to die after being treated?

Algae will be killed within 24 hours of administering a dosage of shock or adding a large amount of liquid chlorine to bring your chlorine level above 10 ppm. After the initial shock keep your pool pump running for 24 hours for the best results. This will cause the green algae to die and will begin to turn into a white color rather quickly.

Depending on how much algae has grown in your pool, the water could also begin to become cloudy as the dead algae begin to be removed from the walls and floor of the pool. It can take a few days to completely restore your pool water to the crystal clear oasis you and your family love.

Brush Algae From Walls

If you caught your algae outbreak in time, you may not have to clean it from the walls and floor nearly as much. However, if the algae has been in the pool for awhile chances are there will be some that has latched onto pool surfaces.

This could include the walls, floors, ladders, and even skimmer, pump, and plumbing system. If this is the case you will need to use a brush to scrub the dead algae from these surfaces.

It can take some elbow grease and force to remove the toughest algae in the most hit areas. If the pool water begins to become more cloudy while scrubbing, you may need to run the pump and allow the algae to settle on the bottom.

Once it has settled, resume scrubbing until you no longer see dead algae on surfaces.

Add Clarifier

This is not always required, but in many instances your pool water will become a milky and cloudy pond after killing an enormous amount of algae from your water. This will lead to a continuous cloudy water that can take a long time to clear up simply by using your pump and filtration system.

Adding a small amount of Pool Clarifier will increase this process dramatically, allowing your water to become clearer in just days or even hours instead of taking what could be multi-week process.

Clarifier can also be added routinely on a weekly basis or as needed if you are having some degree of difficulties maintaining sparkling clear water.

Let Algae Settle

After you have cleaned the algae from the surfaces of your pool and added some clarifier if needed, allow the algae to settle to the bottom of the swimming pool. This can take a few hours, or even up to 12 hours depending on the severity of the original algae outbreak.

During this time allow the pool pump to continue to circulate the water so that the pool filtration system can work at restoring the pool’s water to beauty by removing the algae that you have killed.

If you added clarifier, you will notice a fairly quickly transformation from cloudy, to partially cloudy and eventually clear water as the pump circulates the water.

Vacuum Dead Algae From Pool

At this point, your water should be clear enough so that you can see the majority of the way (if not completely) to the bottom of your pool. If you have a large number of dead algae (or even a small amount), it may be a good idea when setting up your vacuum to use a waste option if available when removing the dead algae.

Some filtration systems, including sand filters, may not be able to catch all of the large amounts of algae that have landed on the floor of your pool allows some to re-enter the pool water.

Even filtration systems such as cartridge filters may stop the majority of all the algae but could be clogged up at a much quicker rate. Bypassing the filter and sending it straight out of the pool to your drainage system could prove to be a much easier experience without having to worry about some of it returning back into your pool’s water and making it cloudy again.

If you do not have a waste option, you may need to clean your filter or backwash your sand prior to completing the entire vacuuming process. It also may take more than one vacuum cycle to remove all the algae if your filter gets overwhelmed and cannot catch it all the first time around.

Treat Pool To Prevent Additional Algae

Now that you have killed the algae and vacuumed it out of the pool, it is important to prevent it from returning at a later time. This can be done with some simple regular maintenance just about once per week.

The most common way to prevent algae is by keeping your chlorine levels within optimal range at all times. Your chlorine should always be between 1 – 3 ppm. This will ensure that your water stays clear, bacteria-free, and kills any algae that come into your pool’s water before it is able to form.

However, not only should you keep your pool chlorine in this range at all times, once per week you need to perform a shock the same way you did to kill the algae that were in your pool. Pick the same time and day of the week, evening or at night is best when the sun UV is not shining, and add a dosage of a shock to your water.

This will bring your water to above 10 ppm once per week overnight killing any bacteria or algae that is trying to form and prevent any possible algae outbreak. It will also kill any other pathogens that are present in the water keeping a healthy and safe swimming environment week after week.

Algaecide Treatment

You might want to consider adding a maintenance dosage of algaecide from time to time to aid in helping reduce the chance of getting algae in your pool.

While algaecide can also be used to kill algae, it is not the method I recommend as the shock treatment will do a much better job once you have an algae infected pool.

It does however help in preventing algae by simply adding a small dosage each week.

Final Thoughts

If you own a swimming pool, chances are you have had algae take over at some point and if you haven’t your time will one day come.

Whether you had a pump malfunction, lack of proper filtration, chemical shortage or simply forgot to add chlorine when your pool turns green it can be cleared up quite easily.

Add some shock, clarifier and give it a nice scrub and let the pump do its magic so you can once again enjoy a nice clear pool and have some family fun.

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