When To Add Algaecide To Pool Water (How Much Exactly)

So, you’ve got a bit of an algae growth forming in your pool and now you’re unsure of how to fix the problem? Well, the good news is you can eradicate and prevent more algae from growing by using the proper chemicals. Algaecide is one of those quick and effective chemicals that are most commonly used to treat algae overgrowth. 

To nip your algae problem in the bud, simply use it at the first sign of algae growth. You can also use algaecide weekly as a preventative measure to ensure no new outbreaks attack the integrity of your pool. As a general rule of thumb, you can measure roughly 16 oz of algaecide for a 10,000-gallon size pool.

Learn all about algaecide and its benefits when you use it weekly. There are several different kids. So, which kind is right for me? Read on to get all the basics and acquire the knowledge you need to use algaecide effortlessly. 

What is Algaecide? 

Algaecide is a copper-based chemical that derives from copper sulfate. Its primary purpose is for preventative measures- prevent new algae from forming and taking over your pool. However, it can be used in a pinch to eradicate algae overgrowth. 

While algaecide does hold the strength to kill algae and is essentially poisonous to the pesty growth, they mostly stunt the growth of new algaecide that may form in your pool. The effectiveness of algaecide is due to its copper metal atoms which work hard to fight against new algae, protecting your pool from an outbreak of unwanted patches.

Algaecide is mostly effective when used as a resource for preventing algae growth altogether. If you are in search of a reactive chemical, this may not be the only solution. However, this chemical is regularly used in pools because of its highly effective compounds that you can rely on to protect your pool from algae outbreaks.

In addition, o matter how severe, it is not advised to swim in a pool with algae. A large volume of algae in the swimming pool encourages the growth of dangerous bacteria that consume algae.

Pros & Cons of Using Algacide

Eliminates Algae effectively
mostly safe for plants and fish with some exclusions affordable
Some algaecides are harmful to fish such as KoiIt can sometimes increase ammonia levelsMildly corrosiveShort Term Solution

Different Types of Algaecide 

There are three main types of algaecide, and other types for various water sources as well. The three that are most worth mentioning when it comes to the care and keeping of your pool are Sodium Bromide, Metallic Pool Algaecide and Quat Pool Algaecide. These three are most commonly used in pools for algae concerns. 

Sodium Bromide 

While sodium bromide is technically not an algaecide, it is equally as effective at attacking algae organisms quickly. This ideal catalyst can rid your algae-filled pool in a pinch and is the perfect reactive solution.

It specializes in eradicating yellow and green algae growth so if you are dealing with either of those, sodium bromide is a trusty tool. This chemical compound is made of sodium and bromide ions and will help fix your problem, but doesn’t hold any preventative purpose. This is the main difference between sodium bromide and traditional algaecides.

Sodium Bromide Algaecide 
Sodium BromideBest for severe cases of algae growth
Works well on green and yellow algae
Cost effective algae solution
Does not always prevent new growth
Is not ideal for black algae
Can decrease chlorine levels so extra maintenance may be required

Metallic Pool Algaecides 

This common type of pool algaecide is a chemical compound mixture of copper ios and amino acids. Positively charged ions attack the algae and the nucleus, responsible for the outbreak. This powerful chemical is a great solution for algae overgrowth and can work fairly quickly. 

Metallic Pool Algaecides 

This algaecide is typically used for black algae and algae blooms. Copper based algaecides have been proven to be the most powerful algae fighting chemical on the market so you can trust that this algaecide will do the trick with no problems. 

Metallic Pool AlgaecideHighly effective
Excellent at eradicating black algae
Ideal for small amounts of algae
More expensive than other types

Quat Pool Algaecides

This popular go-to algaecide is also known as Quaternary Ammonium compound. This microbial disinfectant compound is positively charged and attaches itself to negatively charged algae, disintegrating the algae altogether.

This algaecide is more popular due to its cost effective rates and high ability to help eradicate the algae problem quickly and prevent new algae from coming back. Different concentration levels help you to achieve your solutions- choose a 10% or 50% concentration level depending on the severity of your overgrowth. Clorox is one of the top brands and is a budget-friendly blend.

Quat Pool Algaecides
Quat Pool AlgadeHighly effective
Ideal for iron-stained pools
Most affordable type of algaecide
Mildly corrosive


When Should You Add Algaecide to Your Pool? 

For starters, if you’re looking to remain proactive and prevent and further algae growth, using algaecides each week will certainly help you to do that. Whichever compound you decide to go with, it should always be used after a shock treatment to any pool and weekly to protect from algae outbreaks. 

If you’re looking to treat your algae, you can add algaecide any time you start to see this pesky growth. Even though this isn’t always the ideal solution, algaecide tends to effectively reduce algae in a quick manner.

How Much Algaecide Should You Use? 

The amount of algaecide you use in your pool will be dependent on the size and amount of water in your pool. Keep in mind that general measurement for a 10,000 gallon pool is 16 ounces of algaecide. Always use this as a guideline for choosing the right amount for your pool. 

Please refer to the chart below to help you learn the safe amounts of algaecide you should be adding to your pool. 

Pool Size5,000 Gallons10,000 Gallons20,000 Gallons30,000 Gallons
Algaecide (oz) Ounces12 oz16 oz32 oz48 oz

How to Add Algaecide to Your Pool 

Once you’re ready to add algaecide to your pool, you’ll want to know how to safely and accurately use it. These steps will ensure you’re taking all the precautions, checking your chemical balance and measuring it out properly. 

Step 1: Test and Balance the Chemicals in Your Pool 

This part is essential to safely maintaining any pool. Keep it in its healthiest form by testing regularly- especially when you’re about to add more chemicals to it. Grab a test strip pack from your local hardware or pool supply store to see if your chemicals are balanced. Match it to the color chart and the back to ensure you’re where you’re supposed to be. 

Step 2: Decide What Type and How Much 

This will be dependent on your situation. If you’re dealing with black algae, you’ll want to opt for a metallic option. For green algae, sodium bromide and Quat algaecide are both proven effective. Use the above chart and read all instructions on the back of your product to help distinguish a safe and proper amount. As long as your levels of alkalinity are a good amount, adding new chemicals shouldn’t be an issue. 

Step 3: Add Algaecide to the Pool

Ensure your filter is up and running as you drop the algaecide into your pool. Circulation is key so make sure it runs at least four hours before turning it off. Add your chemicals as per instructions and guidelines for safe amounts. 

Step 4: Vacuum the Pool 

If you’ve been a pool owner for some time, you know the importance of vacuuming your pool. Once you’ve added new chemicals, it’s essential to vacuum regularly to keep unwanted particles and bacteria from creating new algae or growths in your pool. 

Once you’ve added your algaecide, you can vacuum your pool as normal. Ensure to hit all of the nooks and crannies, ridding any visible algae on the walls and floor of your pool. Regular maintenance of the pool surfaces is key to keeping it clean and healthy. 


Now that you know the benefits of algaecide and how it works, you will have everything you need to attack your algae problem head-on at the sight of an overgrowth.

Using algaecide is proven effective when used as a preventative measure as well so weekly additions of this chemical will help keep your pool clean and healthy. Always read the instructions on your products and use the base measurements as a guideline for adding safe, proper amounts for effective results. 

Final Tip: Be sure to store your algaecide solutions in a cool dark place with an air-tight fitted lid, ensuring that no air compromises the integrity of the chemical compound. 

Leave a Comment