Algaecide vs Chlorine: Which One Should You Use?

People often get confused about the use of algaecide and chlorine since their core purpose is the same, removing algae from the pool. However, they are different from each other. Their ingredients, working methods, and usages are different.

Knowing their differences will let you apply the right chemical to fight against the algae. For example, using algaecide when algae are growing will not work. Algae is meant to prevent algae, not kill algae.

This writing will help you understand the core differences between Algaecide vs chlorine so that you can apply the right one for algae protection.

Algaecide vs Chlorine

What is Algaecide?

Algaecide is a chemical element that hinders algae’s growth in water. Its chemical compounds are very effective for fighting against algae. Algaecide is recommended when you can’t take care of your pool water & algae grows up. Synthetic algaecide ingredients are benzalkonium chloride, copper sulfate, dichlorophene, hydrated lime & many more chemicals.

There are both natural & synthetic algaecides available. But, synthetic algaecides are widely used for the disposal of algae. If you haven’t had a past history of metal staining in your pool, you should go for copper-based algaecides. Besides, you have an option for using quat algaecides which slows down the growth of algae.

Algaecide ingredients

Synthetic algaecide uses some ingredients. These ingredients help to prevent algae spreading. Let’s see the list of algaecide ingredients.

Benzalkonium ChlorideCybutryneFentin
BethoxazinDichloneHydrated Lime
Copper SulfateDiuronIsoproturon
NabamOxyfluorfenPentachlorophenyl Laurate

How Algaecide Works

Aside from the swimming pool. algaecide is also used for fish ponds. Let’s learn how algaecide works. Copper-based algaecide has dissolved copper. When you apply it to your pool or pond water, you’re adding copper in the water. It works by attacking algae colonies & destroying their heredity.

Copper removes nutrients included in the algae tissues. Algae can receive water & sunlight to continue their photosynthesis process but copper is toxic for them & hinders the process. Perhaps, it works by causing algae cell walls to burst. As a result, they can’t produce food by photosynthesis & die.

When should you use Algaecide in your pool?

If you are determined to kill algae from your pool, let’s learn when you should use an algaecide in your pool.

  • After shocking the pool, your pool contaminants are removed. But, it’s not over anyway. You need to add algaecide to your pool weekly so that algae can’t grow up.
  • When you close your pool for a very long time, it’s good to add algaecide. Your pool may get affected by algae in the interval.
  • When you open your pool after a long time, you must find that your pool is attacked by these phytoplankton. If you want to swim smoothly, you must add algaecide to protect the pool water.
  • Dark & moist weather are helpful for algae growth. So, don’t let your pool touch these. If accidents happen, then you need to shock your pool & need to add algaecide.
  • After a heavy rain or storm, derbies come to your pool. If your pool isn’t covered, then you have a chance of algae attack. So, don’t forget to use algaecide treatment.

What is chlorine?

Chlorine is a powerful halogen element. It kills the germs of the water by forming a chemical reaction. It’s widely used for pool shocks. That’s why it’s popular as a sanitizer.

Chlorine produces hypochlorous acid that works against the bacteria like E.coli. Bleach & chlorine used for pool shock are identical. The difference is in the strength.

How does chlorine work?

Chlorine works by performing some basic chemical reactions. It breaks the chemical bonds of the algae. Chlorine actually works when it comes in contact with enzymes. Enzymes act as a catalyst & it’s a vital part of organic life.

When an algae cell doesn’t receive enzymes properly, it dies immediately. The reaction produces under the chloric acid & as a result, the cell walls of microorganisms like algae get affected.

When should you use chlorine in your pool?

There are some facts you should use chlorine in your pool. Have a quick visit to the facts.

  • From the winter to the spring season, definitely your pool remains closed. When you want to reopen it at the beginning of summer, you will see the mastery of algae. So, applying chlorine shock becomes mandatory.
  • When external bacteria are added to the pool, the chlorine level decreases immediately. Sometimes you may do a little party & people may spread bacteria. To get rid of this problem, using chlorine becomes essential.
  • In the summer season, algae grows in hot weather. Sunny weather isn’t good for you but algae. The extended temperature decreases the power of chlorine & you need to add it up.
  • Heavy raining decreases the acidic environment & in that case, pH becomes high. A high pH level decreases the power of chlorine & causes the spread of algae. In that case, adding up chlorine is a must.
  • When your eyes get irritated & you feel the smell of chlorine, it means combined chlorine is increased. It’s dangerous for the pool water & you need to apply chlorine shock then.
  • Pool closing is a plan for a long time & in that time period, your pool may be affected by microorganisms. So, before closing your pool, don’t forget to apply chlorine shock.

The main differences between chlorine and algaecide

To understand the basic differences between chlorine & algaecide, go through this part.


Algaecide is a chemical compound that forms with some chemical ingredients including copper sulfate. Its copper hinders photosynthesis & destroys algae colonies. On the other hand, chlorine is a halogen element that produces salt after the reaction. It damages the enzymes & kills bacteria.


Algaecide works as a backup chemical. Algaecide removes oxygen from the algae & forces them to die. It should be added after shocking the pool. But, chlorine is used to shock the pool. When chlorine is applied, it breaks the chemical bonds of bacteria. Under chloric acid is formed after applying chlorine & combining with hypochlorite ion, it forms free chlorine to the pool water.

Action time

Algaecide works slowly. There are different types of algae to fight against. If your pool is attacked by yellow algae, your algaecide will need enough long time to prevent. It takes around 2-3 weeks to prevent.

On the other hand, chlorine starts to work faster than algaecide. Our fight is against algae-like E.coli bacteria & chlorine needs only less than one minute to kill the algae. If it’s the fight against hepatitis A virus, it will take around 16 minutes for chlorine. When the pool is affected by Cryptosporidium, you’ll need up to 10 days.

Prevention vs remedy

Algaecide is used to prevent. It’s okay to use for remedying the spread of bacteria but it’s better to use for prevention. Who doesn’t want to win a war against algae within a short time? As the algaecide works slowly, it can be used for prevention. But, if your pool is already attacked by the algae, you need to remedy it. You must remedy it using chlorine for a fast response.

Algaecide is constructed with a combination of varieties of chemicalsChlorine is a halogen element
Algaecide works as a backup after chlorine shockChlorine is used to shock the pool water
Algaecide starts to kill germs slowlyChlorine goes to action within 24 hours
As an alga preventing item, algaecide is widely usedChlorine is widely used for decreasing the remedy of the algae problem.

So, Do I need algaecide or chlorine for your pool?

Well, if you are already attacked by algaecide, you must need chlorine for your pool to kill those algae. Besides, when the chlorine level of your water is down, you need to apply chlorine immediately.

On the other hand, algaecide is suitable for preventing algae in your pool. Also, if you are thinking of maintaining your pool regularly, using algaecide is a good choice. That means chlorine is your remedy for algae and algaecide is a way to prevent algae. Now you decide your current pool position and then apply any of these to make your pool free from algae.

Some people have confused about using algaecide & chlorine altogether. It’s strictly prohibited because it makes all of your effort useless. So, apply chlorine to kill germs in a short time & then, add algaecide maintaining a weekly routine.

Let’s know some answers to common questions.

Are algaecide and chlorine the same thing?

Not at all. Algaecide is a chemical element with copper sulfate. It contains copper inherits the spread of algae. On the other hand, chlorine is a sanitizer that can be used for pool shock.

Do I use shock or algaecide first?

You must shock first. After completing the shocking, you are safe from algae attack for a short time. You need to take regular care of your pool using algaecide is part of it.

Does algaecide affect chlorine?

Yes, algaecide affects chlorine. When it’s used together, it doesn’t work with their exact chemical reaction make all the effort useless.

How long after algaecide can I add chlorine?

You need to wait until the chlorine level goes down to fall below 5 PPM. Other than that, it is too risky to use algaecide right after using chlorine in your pool.


What’s about your realization now about algaecide vs chlorine? Yes, both are different in purposes & chemical balance. Algaecide assists as a guard after shocking your pool. On the other hand, chlorine destroys the algae spread. People make the mistake of not using algaecide after using the chlorine shock. You mustn’t make this mistake.

It’s no more a matter of confusion after going through this article. Besides, we have tried to show you how to clean algae with chlorine & how to control algae. You also know how much shock you need to use with different types of algae. So, if your pool is affected by algae, just follow the instruction of this article.

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