Algaecide or Shock First

While shocking and adding algaecide is very effective in killing off algae, they should not be done together. This is because when you mix chlorine and algaecide, it renders both of them useless. There is a sequence of treating a pool with stages of algae. Which chemical do you add first? Algaecide or Shock?

You should first shock/super chlorinate your pool to levels above 5 ppm-scrub the walls & floor of your pool then wait for the chlorine levels to fall below 5 PPM. When they do, add algaecide to your pool. This will kill off the rest of the algae and provide a preventative solution to your pool H2O. 

The secret, my experience, especially in a bigger pool, is to brush the pool floor, steps, and walls with a long handle pool brush and add chemicals in sequence If a green pool develops get right on it before it gets worse because it only will and read this article for complete instructions.


Algaecide or Shock First

Add Shock Chlorine

Heavy shocking with granular chlorine will generally require 24-48 hours above 5 ppm before the chlorine demand level has dropped to safe swimming levels (below 5 ppm). Add Algaecide

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Add Shock Chlorine before Algaecide

The right dose of Chlorine kills algae and realistically acts like an algaecide when you add it to the pool water. If the chlorine is balanced, Shock first. Algae should not be a huge problem. Unfortunately, Algae is stubborn and looks for ways and places to grow.

For this reason, using an Algaecide after a huge dose of chlorine can help keep them away, and if your pool succumbs to algae can help clean up the mess much faster. Follow this article that will help you through what all pool owners go through.

Like chlorine, algaecides also kill algae, but they typically work more slowly.

You should start seeing a transformation after 24 hours. If you have green pool water after shock, it is imperative to think about your water and pool safety. Hence, don’t use the pool after 24 hours. First, do another pH test to get clearance, and then backwash your filter a final time, and you are good to go.

*All algaecides work by releasing positive-charged ions into the water, which combine with the negatively charged algae particles. Algaecides don’t break down in sunlight the way chlorine does, so they remain available much longer. Some algaecides are preventative and won’t remove algae once they establish themselves in your pool.

The best way to deal with a green algae-filled swimming pool is to super-chlorinate the pool and then add algaecide to the pool water. It’s going to take some time to do this.

Most algaecides are not intended as a standalone treatment against intense algae problems but are rather intended to be used preventatively or as a follow-up to other treatments like shocking or super-chlorination 


Different Types of Pool Algaecide


Algaecides are important chemicals used to control algae growth in pools. There are various types of algaecides available, each with its own characteristics and recommended uses. Here are some different types of pool algaecides:

  1. Quaternary Ammonium Compounds (Quats): These are the most common types of algaecides used in pools. Quats work by disrupting the cell membranes of algae, ultimately killing them. They are effective against a wide range of algae types and are relatively inexpensive. However, they can foam in certain conditions and may require additional clarifiers to combat this.
  2. Polymeric Algaecides: Polymeric algaecides are long-lasting and effective against a broad spectrum of algae types. They work by forming a protective barrier on the surface of the pool, preventing algae growth. Polymeric algaecides are often used for preventative maintenance and can last for several weeks.
  3. Copper-Based Algaecides: Copper-based algaecides utilize copper ions to kill algae. They are effective against most types of algae but can stain pool surfaces if used in excess. Additionally, high levels of copper can be toxic to aquatic life, so these algaecides should be used with caution and according to manufacturer recommendations.
  4. Silver-Based Algaecides: Silver-based algaecides work similarly to copper-based ones but use silver ions instead. They are effective against a variety of algae species and are less likely to cause staining compared to copper-based algaecides. However, they can be more expensive.
  5. Non-Metallic Algaecides: Non-metallic algaecides contain active ingredients that do not rely on metals like copper or silver. These algaecides are often used in situations where metal staining is a concern or in pools with sensitive equipment. They can be more expensive than metallic algaecides but offer a non-staining alternative.
  6. Chlorine-Based Algaecides: Some algaecides contain chlorine as their active ingredient. These products not only kill existing algae but also help to sanitize the pool water. They are effective against most algae types but should be used cautiously to avoid over-chlorination.
  7. Enzyme-Based Algaecides: Enzyme-based algaecides work by breaking down organic matter in the pool, which can help prevent algae growth. They are often used in conjunction with other types of algaecides for enhanced effectiveness. Enzyme-based algaecides are typically safe for use in all types of pools.

When choosing an algaecide for your pool, consider factors such as the type of algae present, the severity of the infestation, and any specific requirements or restrictions for your pool type. Always follow manufacturer instructions and dosage recommendations for safe and effective treatment.


 Pool Algae in Swimming Pool

The first signs of Algae may not look like algae.

Algae is a single-celled plant form. It uses the process of photosynthesis to make its own food. It comes in a very wide variety of colors and forms and is adaptable to almost all conditions. Because of algae’s microscopic size, it takes millions of these plants to accumulate to be noticed by the naked eye! By that time, it may be too late and very costly to correct.

The best way to eliminate algae is through prevention!  Don’t let it start, but if it does, then Jump on It!  Algae happen in in-ground pools, above-ground pools, freshwater pools, and saltwater swimming pools.

There are 3 main types of Algae associated with a swimming pool:

  • Green algae- can cling to the wall or float in the water. Get rid of it by brushing the sides and floor of the pool, shocking, and adding Algaecide. The most common type of algae causes you to notice green water in your pool. They are caused by a lack of proper filtration and sanitation, which often leads to an elevated pH level in the pool.
  • Black algae- looks like black spots and feels slimy. Get rid of it by brushing the algae and adding Algaecide- Such algae can appear in your pool if someone, before entering the pool, swam in a natural body of water (ocean, river, lake, etc.) and did not wash their swimsuit after that.
  • Mustard algae- looks like sand on the floor of the pool. Get rid of it by brushing the algae and adding algaeecide. They are more common in southern countries than in northern ones. However, yellow algae (also called mustard) can appear in all pools. If the pH or alkalinity of your pool is abnormal, this may be the cause. Debris, phosphates, and pollen can also cause yellow algae.


Here’s a table outlining different types of pool algae commonly found in swimming pools along with their characteristics and treatment methods:


Type of Algae Characteristics Treatment
Green Algae – Appears as green patches or slimy greenish coating on pool surfaces – Shock treatment with chlorine- Brushing and vacuuming Algaecide
Black Algae – Dark green or black spots embedded in pool surfaces, especially on plaster or grout joints – Aggressive brushing to break algae’s protective layer Algaecide
Mustard (Yellow) Algae – Yellow or mustard-colored patches on pool walls and bottom – Shock treatment with chlorine- Brushing and vacuuming- Algaecide
Pink Algae – Pinkish-red spots on pool surfaces – Shock treatment with chlorine- Brushing and vacuuming- Algaecide
BlueGreen Algae – Bluish-green or cyanobacteria mats floating on the water surface – Shock treatment with chlorine- Algaecide


Remember, prevention is key to avoiding algae growth in swimming pools. Regularly maintaining proper water chemistry, circulation, and sanitation levels can help prevent algae from establishing in the first place. Additionally, routine brushing and cleaning of pool surfaces can help disrupt algae growth and prevent it from taking hold.

First, before using a pool algaecide, analyze and balance the swimming pool water.

  • If the pool is full of algae, add a flocculant (floc) to the water and vacuum up the coagulated algae that settle on the bottom of the pool.

Before and during treatment, you should thoroughly brush the algae to “break open” the slime layer. This is an important step. If you skip it, you’ll prevent the treatment from working.

Shock the pool very aggressively. As a guide to follow, shock treatments should be used before algaecides start the process. Wait for the residual to come down and brush the algae to loosen.  Add substantial amounts of strong Algaecide. Once the chlorine level rises in your swimming pool water after adding shock chlorine, you will see the swimming pool react Keep pool filters running in fresh or salt water pools.

Add Pool Algaecide After Pool Shock

Add Algaecide

You do not need to wait for your pool to go green before you Shock it. In fact, you should Shock your pool every week. In the summer, don’t wait longer than two weeks. But what about Algaecide? Do you add Algaecide Before Or After Shocking your pool? Once the pool is shocked and the residual comes down below 5ppm, go to step 2.

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Add Algaecide after Shock Chlorine

Algaecide should always be added after Shock. Shock is considered complete only when your pool loses less than 1 ppm of chlorine overnight. Add algaecide only after the chlorine level has dropped to 5 ppm or less. High levels of chlorine make the active ingredients of algaecide ineffective. Algaecide should be used after each shock treatment.

A Small amount to a large amount of algaecide should be added after every shock treatment for a quick treatment process. 

The role of algaecide to kill algae is secondary. The primary role of algaecide is to prevent the growth of algae growth in the next 5 – 7 days after shock. To be effective in this role, the algaecide should be well dissipated throughout the pool. Algaecides usually require a shock treatment before application anyway, so just be sure to shock the pool first.

It is very important to run the pool filter & pump while adding Algaecide. It is best to start the filter pump just before adding Algaecide and let it run for 2-4 hours to ensure adequate circulation. If white foam develops on the surface of the pool, it will dissipate after a while with the filter on.

Your pool water pump should be left running for about 24 hours following the addition of an algaecide in order to get the products adequately circulated, so be sure to override your pump’s timer if you have one set up.

* Depending on the number of algae that is killed, You may have to use a Flocculant chemical that adds weight to the suspended solid, which will help settle these solids to the pool bottom to be vacuumed out of the pool.

Or use a Clarifier chemical, sometimes called a Pool Water Polisher, for fewer amounts of solids suspended in pool water that will make solids bigger so that they are trapped in the filtering system.

How Long Does it Take for Algaecide to Work


The time it takes for algaecide to work in a swimming pool can vary depending on several factors, including the type and severity of the algae infestation, the specific formulation of the algaecide used, and the pool’s water circulation and filtration system. In some cases, algaecide can begin to show visible results within hours of application, particularly for milder cases of algae growth.

However, for more stubborn or severe algae blooms, it may take a day or longer for the algaecide to fully eradicate the algae and restore water clarity. It’s important to follow the manufacturer’s instructions regarding dosage and application frequency to ensure optimal effectiveness.

Additionally, proper water chemistry maintenance, regular brushing and vacuuming of pool surfaces, and adequate circulation and filtration are essential to support the algaecide’s effectiveness and prevent algae from returning.

Algaecide acts in the pool for five to seven days. Watch your pool for several days, and run the pump regularly to see if the mold comes back. After five-seven days, you can add algaecide in low concentrations as a preventative for algae control. Shock can complete the algae removal process.

During the hot summer months, adding a copper-based algaecide can be a preventative while keeping your home pool open. If you add too much algaecide, foam appears, but note that it will dissipate over time.

The pool algaecide will slowly fade due to chlorine, so you can shock the pool with higher chlorine levels to speed up the process and wait a few days after the shock. Even if you do not do this after you add algaecide, the cloudiness, which is pool algae, will disappear in about a week or two at the most.

Although the algaecides that are used for most pools are low in concentration so that you can swim right away, it is advisable to wait a few minutes to an hour. Let the product spread throughout the pool, especially if it has copper in its composition, since you don’t want to have colored hair, right?


Adding Algaecide to Swimming Pool


If you use an Algeacide step by step correctly, as well as calculate the correct dose for your pool and not overdo it, algaecides you can consider it a safe product for your health. You can even swim with it, but remember that it is always better to wait for a little while before immediately swimming.

Adding algae acid in a swimming pool to kill or prevent algae from growing in your swimming pool would be the best way to offset any type of algae. Using a chemical calculator for Algaecide, pool shock, or pH chemicals is the best function of preventative maintenance.

Its job is to interrupt important processes inside the algae, stopping photosynthesis or provoking an explosion of the algal cell walls. It is best to use an algaecide in combination with a chlorine sanitizer to keep the pool water clean.

Most algaecides are copper-based, which are chemical compounds with metal as the central atom. Such a chemical disrupts the normal cellular processes inside the algae, thus killing them and preventing them from developing.


  1. Make sure all of the filtering systems of your pool, including the pool pump, are working properly.
  2. Before adding algaecide, the chlorine level in the pool should normally be between 1 and 3 ppm, parts per million.
  3. Super-chlorinate the pool water and let it stand for 24 hours until it returns to a safe level.
  4. Add the correct amount of algaecide to the pool following the instructions on the package. For the best results, use the online algaecide calculator.
  5. Leave your pool to sit after adding algaecide for 12 or more hours or overnight and vacuum all dead algae in the morning.
  6. Adjust your pool pH and keep a close eye on chlorination levels.  If the concentration is above 6 ppm, the pool is still unsafe to swim in.
  7. Add algae concentrate or copper chelate solution to the water, depending on the needs of your pool.
  8. Mix it in a bucket with pool water and broadcast, covering the circumference of the pool surface.

Using Algaecides for Algae Control


Algaecides play a crucial role in algae control maintenance for swimming pools, helping to prevent algae growth and maintain water clarity. Here’s how to effectively use algaecides as part of your pool maintenance routine:

  1. Choose the Right Algaecide: Select an algaecide suitable for your pool type and the specific algae you’re dealing with. Consider factors such as the type of algae (green, black, yellow, etc.), the severity of the infestation, and any specific pool requirements or restrictions.

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  2. Follow Manufacturer Instructions: Always read and follow the manufacturer’s instructions and dosage recommendations carefully. Using too much or too little algaecide can be ineffective or even harmful to swimmers and pool equipment.
  3. Maintain Proper Water Chemistry: Ensure that your pool’s water chemistry is properly balanced, including pH, chlorine levels, and alkalinity. Balanced water chemistry creates an environment that is less conducive to algae growth and enhances the effectiveness of algaecides.
  4. Regular Application: Incorporate algaecide treatments into your regular pool maintenance schedule, especially during peak algae season or after heavy pool usage. Weekly or bi-weekly applications of algaecide can help prevent algae from establishing and keep your pool water clear.
  5. Brushing and Vacuuming: Prior to applying algaecide, thoroughly brush and vacuum the pool surfaces to loosen and remove any existing algae or debris. This helps the algaecide to penetrate more effectively and target algae growth.
  6. Shock Treatment: In conjunction with the algaecide application, consider performing a shock treatment to boost chlorine levels and eliminate any existing algae. Shocking the pool helps to quickly kill algae and other organic contaminants, improving water clarity and sanitation.
  7. Maintain Proper Filtration and Circulation: Ensure that your pool’s filtration and circulation system is operating efficiently. Proper circulation helps distribute algaecide evenly throughout the pool, while filtration removes dead algae and other debris.
  8. Monitor and Adjust: Regularly monitor your pool water for signs of algae growth or imbalances in water chemistry. Adjust algaecide dosage and frequency as needed based on pool conditions and environmental factors.

By incorporating algaecides into your pool maintenance routine and following these guidelines, you can effectively control algae growth, maintain water clarity, and enjoy a clean and inviting swimming pool.



You should first shock/super chlorinate your pool to levels above 5 ppm-scrub the walls & floor of your pool then wait for the chlorine levels to fall below 5 PPM. When they do, add algaecide to your pool. This will kill off the rest of the algae and provide a preventative solution to your pool H2O.

The secret, my experience, especially in a bigger pool, is to brush the pool floor, steps, and walls with a long handle pool brush and add chemicals in sequence If a green pool develops get right on it before it gets worse because it only will and read this article for complete instructions.


How Long After Adding Algaecide Can You Shock?

While shocking and adding algaecide is effective in getting rid of algae, it should not be done together. When you mix chlorine and algaecide, it renders both of them useless. You should first shock the pool and wait for the chlorine level to become normal (1-3 ppm), after 24 hrs or so, and then add an algaecide.………………………………….. Read more


JimGalloway Author/Editor



In the Swim-Pool Shock: Shocking for Algae Removal



  1. What is an algaecide, and how does it work?  Algaecide is a chemical treatment used to control and prevent algae growth in swimming pools. It works by disrupting the cell membranes of algae, ultimately killing them and preventing further growth.
  2. When should I use an algaecide in my pool?  Algaecide should be used as part of your regular pool maintenance routine, especially during peak algae season or after heavy pool usage. It’s also recommended to use algaecide as a preventative measure to inhibit algae growth.
  3. How often should I apply algaecide to my pool?   The frequency of algaecide application depends on factors such as pool usage, weather conditions, and algae growth. In general, algaecide should be applied on a weekly or bi-weekly basis for preventative maintenance, or more frequently as needed for existing algae problems.
  4. Can I swim in the pool after adding algaecide?    It’s typically safe to swim in the pool after adding algaecide, as long as the product label instructions are followed regarding dosage and waiting times. However, some algaecides may recommend waiting a certain period before swimming to allow the chemicals to disperse and the water to return to safe levels.
  5. Can I mix algaecide with other pool chemicals?   It’s generally not recommended to mix algaecide with other pool chemicals unless specified by the manufacturer. Mixing chemicals can cause dangerous reactions or reduce the effectiveness of both products. Always follow label instructions and avoid combining algaecide with chlorine shock treatments in the same application.




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