Last Updated: May 27, 2022

Remove Algae With Pool Shock

Written By: Pool Care Guide

A clean pool is a happy pool. But sometimes, no matter how often you brush and vacuum, you get algae infestation. Algae are single-celled organisms that live in water and produce oxygen through photosynthesis.

There are more than 30,000 known species of algae. While some algae are essential to the aquatic ecosystem, others can be quite harmful, causing water quality problems.

The best way to get rid of algae is to prevent it from growing in the first place. But if you already have an algae problem, don't despair! One of the best ways to get rid of algae is through shocking.

What Is Shocking a Pool?

"Shock" the pool involves adding high amounts of chlorine or other disinfectants. This kills the algae and prevents it from coming back.

Essentially, shocking the pool should be done weekly. However, if your algae are more severe, you might need to shock your pool repeatedly to achieve the desired purity level.

Preparation for Pool Shock

Before undertaking pool shock, it is imperative to ensure that the pool is in the right condition to achieve the desired results. Here are the steps to undertake when preparing your pool.

Clean the Pool

Generally, the pool is dirty due to high amounts of algae. However, cleaning here means removing any debris, dirt, and other objects that might be present in the pool.

This will ensure that the chlorine you add will not be diluted and will be able to achieve the intended concentration.

Stabilize the PH Level

Chlorine tends to work best at PH levels of 7.2. Therefore, your pool being contaminated will have a much higher PH. Bring down your pool's PH by using muriatic acid or hydrochloric acid.

Before you begin, though, take tests to ascertain the deviation margins; if your pool has a PH lower than the recommended, use sodium carbonate to bring it up.

Determine Level of Algae Attack

The correct amount of chlorine for your pool shock depends on how much algae is present in your pool. Here, the color of your pool will tell you what will be needed.

Light green: The water will generally be clear with a few strands of algae visible. This indicates an onset of algae overgrowth.

Medium green: The water will appear cloudy with many algae visible to the naked eye. This is a moderate level of algae infestation.

Dark green: The water will appear murky with no visibility. This is a severe level of algae infestation.

Chlorine Amounts Needed for Pool Shocking

The amount of chlorine needed to kill algae will vary depending on algae growth, but as a general rule, 1 part of chlorine per million parts of water (ppm) will be sufficient for a clean pool.

Ideally, most pool experts will recommend 1 pound of chlorine for 10,000 gallons of water. This, however, will vary depending on the level of infestation.

 If your pool is filthy or you're dealing with high algae levels, you may need to use more. Sometimes you might need to use upwards of 5 pounds to achieve the desired results.

What if you don't get the desired results? You may ask. Shock the pool repeatedly until the water turns bluish. This will be an indication of a clean pool.

Pool shocking is a delicate and critical procedure. The amount of chlorine used can be pretty dangerous if not done correctly. It is therefore advisable to always seek professional help when in doubt.

Shocking the Pool

Once your pool is well prepared, it is time to begin the shocking process. Here are the steps you need to follow:

Turn off all pool equipment and make sure that no one is swimming in the pool.

Add the required amount of chlorine to the pool. You can do this by pouring the chlorine into a bucket and then adding it to the pool water.

The rule of thumb is to add shock to the water and not the other way around. Dilute the required amount of chlorine after determining the level of algae attack.

Breathing in chlorine, especially in high concentrations, is dangerous. Therefore, it is advisable to wear gloves and a mask to avoid health complications.

Pour in your chlorine solution along the pool perimeter. Do not pour it all in one place, as this will create areas of high concentration which might be difficult to dissipate.

Once you are done, turn the circulation system on and let it run for at least 12 hours. The chlorine will need time to work its way through the entire pool.

After 12 hours, check the chlorine levels to ensure they are still within the recommended range. The ideal level should be between 1 and 3 ppm.

If, after 24 hours, the algae isn't cleared, add another round of shock. Repeat the process until the water turns blueish. Don't worry about the frequency of shocking; it is better to be safe than sorry.

When finally the chlorine kills all the algae, the pool will attain a whitish color. Then, depending on the amount, the algae will settle to the pool floor or float on the surface.

The green color should be gone. Next, run the backwash function of the filter to get rid of the algae. This should be all day round for a couple of days.

It Is Time To Clean the Pool

A couple of days after your shock, the pool should be free of algae. It is now time to give it a good clean.

Start by brushing the walls and floor of the pool to remove any debris or algae that has accumulated.

Use a pool vacuum to suction out all the dirt and debris from the pool. Be sure to vacuum in both directions to get everything out.

After you are done, repeat with a new brush and vacuum the pool again.

It is important to note that you should not use any chemicals in the pool during this process as they might react with chlorine and cause harm.

Install a New Filter

If your pool came with an old filter, now would be a good time to replace it. A new filter will help keep the water clean and clear for longer.

Cleaning your current filter will work just as well. Start by taking it out and disassembling it.

Clean all the parts with a hose or in a bucket of water. Use cartridge filter cleaner if your system uses a cartridge or DE filter. Other types of filters are hard to clean, and where possible, you should replace them.

Balance Your Pool

Once you are done with the filter, it is time to balance the chemistry in your pool. This is an essential step as it will help ensure that your pool water is safe for swimming.

Start by testing the pH levels of the water. The ideal pH level should be between 7.2 and 7.6. If the levels are off, use a pH adjuster to bring them back to normal.

The next step is to test the alkalinity levels. The ideal range should be between 80 and 120 ppm. If the levels are too high or low, you can use an alkalinity adjuster to bring them back to normal.

The last step is to test the calcium hardness levels. The ideal range should be between 180 and 220 ppm. If the levels are too high or low, you can use a calcium hardness adjuster to bring them back to normal.

Now that the water is balanced, you can add pool salt to the water. This will help keep the pH levels in check and make the water feel softer.

Add the required salt to the pool and let the circulation system run for at least 12 hours.

After 12 hours, test the salt levels and add more if needed. The ideal level should be between 3000 and 4000 ppm.

Reintroduce the Algaecide

During shocking, the algaecide was dissolved. So, now that the water is clean, you can add it to the pool.

Start by adding the required amount of algaecide to the pool. This will prevent future outbreaks of algae.

Let the circulation system run for at least 12 hours to ensure evenly distributing of the algaecide. Then, maintain weekly doses of algaecide to keep the pool free of algae.

Tips To Prevent Future Algae Attacks

There are a few things you can do to prevent future algae outbreaks.

The first thing is to ensure that the pool is covered when not in use. This will prevent dirt and debris from getting into the water and causing an imbalance.

Avoid food around the pool area as it can attract insects which then lay eggs in the water.

Another thing you can do is to test the water chemistry regularly and balance it accordingly. This will ensure that the water is always in the ideal range for swimming.

Lastly, you should clean the pool regularly and use an algaecide weekly. This will prevent algae build-up and keep the water clean and clear.

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