Algae in Saltwater Pools – How to Get Rid of ?

If you have a saltwater pool, you will need to maintain it properly. And one of the most common problems is the algae in saltwater pools. But there is no need to despair. Once you read reading this article, you will know everything you need to tackle this issue. 

Do You Need to Add Algaecide to a Swimming Pool With a Salt Water System?

One of the first things you might wonder about is if you need to add algaecide to the maintenance routine of your saltwater pool. The short answer is yes. You need to use algaecide, but let’s see why.

Saltwater pools present a constant risk of developing algae. The algae infest the water and deteriorate the aesthetic aspect of the pool. You will notice that these algae will attach to the walls of the pool, and you will see them easily. You could add chlorine pills to the saltwater to sanitize it as well, but an algaecide is an excellent product to consider. Chlorine alone will not be as efficient as you need it to eliminate the algae residue.

Algaecides are mixtures of different chemicals, including metallic minerals and ammonia as well as chlorine and acid. Some of the metallic minerals efficient in algaecides are silver and copper. These minerals reduce algae found in salt pools as well as pools that use chlorine treatment. You will have to decide what type of algae you need to get rid of before choosing the right strategy. There are algaecide products for both green algae and black algae, as well as other types.

The best algaecide products on the market have a minimum of 30 % active ingredients, meaning ammonia and metal. All you have to do is follow the instructions of the algaecide, and your pool will be algae-free! There is no need to invest in any pool cleaning equipmentif you use these products.

It is essential to mention that algaecides could damage and stain your pool, so you shouldn’t use them in significant quantities.

Algae Types and Impostors

When your saltwater pool gets contaminated, you will deal with different types of algae. If you want to get rid of your algae, you need to be aware of the primary algae types and impostors that could affect your pool. 

1. Green Pool Algae

Some of the most common algae impostors are the green pool algae. Also known as Chlorophyta, these green algae are a type of cyanobacteria. The green color comes from chlorophyll. These green pool algae are fast to reproduce and fill your pool in a short period. One day you will notice the water in your pool being cloudy, and right in a few hours, you will see it turning green.

2. Yellow Pool Algae or Mustard Algae

Another type of algae is the yellow pool algae. These algae are also known as mustard algae, and they can be just as bothering as the green algae. You will notice these algae look like pollen, and it develops on the floor of the pool. This type of algae comes from the xanthophytes microbes family. It is commonly found in southern climes, and you can easily confuse it with dust. This alga is resistant to chlorine and very persistent as well. 

3. Black Pool Algae

Black algae also come from cyanobacteria, and it is not an algae type. But because it contaminates salt pools often and it looks like algae, people refer to it as such. You will notice it in the form of black stains or spots on the solid parts of your pool, such as the floor or the walls. The main problem with black algae is that it can dig into the surface of the walls, and you will find it hard to eliminate. 

4. Pink Slime

The last but not the least type of impostor you might have to deal with is pink slime. This pink slime is not algae but a bacteria that can contaminate your pool fast and be significantly challenging to remove. You should treat it as soon as you notice it because it will only get worse as days pass. Even if pink slime, just like white water mold are not dangerous for people, no one will be thrilled to swim in it. Another thing we need to mention is that pink slime can develop in all pools and not just the saltwater ones. 

Why do I have green pool water?

The first question that will come to mind as you see green pool water ruining your lovely pool will be, why? First of all, there is no need to panic, as you will be able to overcome this problem. Here are the main reasons responsible for your pool water turning green.

  • Not enough chlorine :

    It is a standard method to sanitize your pool with chlorine. This method will not only keep it clean, but it will also keep the green shade away. Water that doesn’t have enough chlorine will be more prone to develop algae. Algae will turn your pool water green in less than 24 hours. This process goes even faster in a warm environment. 

  • Pollen contamination –Pollen can cause the water to turn green as well as yellow. But where does the pollen comes from? If your pool is near trees or flowers, the pollen will be carried by the wind into the pool little by little. This contamination is not something that could happen overnight like algae, but it nevertheless can contaminate your pool water. The pool filter will not be able to remove the pollen because it comes in too small particles. And you might not even realize that your pool is contaminated until it is too late. You will find it easy to confuse pollen with yellow or mustard algae. The good news is that it is harmless for your health.
  • Metal contamination – Some metals are also responsible for turning the water in your pool green. And the most common mineral that can turn water green is copper. You can get copper into your pool by using the wrong algaecides or by using too much of them. If your water is too acidic, it will also facilitate metal contamination through the components of the pool that contain metal. This contamination can damage not only the water in your pool by turning it green but also the lake itself.

How to get rid of pool algae?

As we mentioned above, there are several ways to get rid of algae in your pool. And here are some of the most efficient methods to try!

Method # 1: Get rid of pool algae by shocking

Shocking your pool is probably your best choice. But the amount of pool shocking will depend on the type of algae you are dealing with. You will need a different shocking for light green pool water, dark green pool water, and black, green pool water as well as for pink slime.

  • Light Green Pool Water – If you notice light green pool water, you should start treating it right away to avoid further contamination. Shocking, it is your best option when you need to eliminate algae. First of all, you have to control the pH level in your pool as algae thrive on high pH levels. Lowering the level of your pH is possible by using hydrochloric acid. You will not need more than one or two liters of it. All you have to do is add one liter of this acid every 24 hours. But make sure you don’t let it get in contact with your skin because it is very toxic.  Shocking your pool by using chlorine is also the right choice. You will need 400 grams of granulated chlorine. You can also use three tubs of 15 L chlorine because these tubs contain 80% water and only 30% chlorine. On the other hand, if you have a saltwater pool that already uses a chlorine sanitizing system, you will just have to add between two and four bags of salt. Make sure the chlorine system is turned on to 100% for this shocking to be efficient. This method will take several days, but if your pool sanitizing system works correctly, you should see the results you want.
  • Dark Green Pool Water –If you have dark green pool water, you will need to follow the same shocking method as for light green pool water. However, while the technique remains the same, the quantities increase. So, you will use more acid as well as more chlorine. The acid quantity will increase to two or even three liters that you will have to add in the time of 48 hours. Consequently, you will have to use about 600 grams of granulated chlorine.  It is essential to remove any existing debris from the floor of your pool before starting this shocking method. This debris can also be responsible for the dark green shade of your pool water.
  • Black Green Pool Water – If you are dealing with black, green pool water, you will need to shock your pool more aggressively. You will follow the same strategy for other shocking levels, but you will increase the quantity three times. So, all you have to do is take the acid and chlorine quantities you would use for light green pool water and multiply it by three before treating your pool.  It will take longer to clean black, green pool water too. So, you can expect to spend about two or even three weeks taking care of it. Make sure your pool filters are clean as well and get rid of any debris that might be present in the pool. Use a leaf shovel as well as a vacuum to eliminate the waste properly.
  • Pink Slime –To get rid of pink slime, you will need to clean your pool as well as possible first. Perform a manually cleaning process that involves cleaning the filter system as well as the return jets and skimmer. You will also have to check the pH in your pool. This pH should be between 7.4 and 7.6, and the level of alkalinity should be about 100 to 150 ppm. Pink slime is very resistant to chemicals and cleaners. This reason is why you will have to use about four pounds of calcium hypochlorite for each ten thousand gallons of water.

    To seal the shocking method, you will have to let your filter run for a cycle of 24 hours. Clean the filter afterward, and your pool is suitable to be used again!

How to shock a saltwater pool?

Whenever you need to shock a saltwater pool, you can follow these steps. They apply regardless of the type of algae you need to eliminate. First of all, you might want to consider shocking your pool water every week just to stay on top of potential algae issues.

  • Test the levels of your pool water

Before you apply any shocking treatment to your pool, you need to know what the initial levels are. You should check the pH level as well as the alkalinity level in your pool. Don’t forget about the calcium hardness level, either!

Once you find out what your levels are, you will know how to adjust them to shock your saltwater pool correctly.

  • Adjust your chemical levels in your pool

There are three simple levels you need to have in mind when you adjust your chemicals. The pH should be between 7.4 and 7.6, the alkalinity should stay between 80 and 150 ppm, and the calcium hardness should not go out of the range of 200 to 400. You should test the level of chemicals after you adjusted them to be sure that you did the changes right.

  • Add the right shock amount

As we saw above, different levels of green water will call for different shock amounts. Examine the type of green water you need to clean and adjust your chlorine as well as the acid you use accordingly. You will have to know the number of gallons you have in your pool. Most cleaning products like chlorine, specify in the instructions how much you should add per a certain amount of gallons. As a general rule, try to get to the chlorine breakpoint of 30 ppm to be on the right track.

It is wise to turn the filter on when you shock your pool as it will speed up the efficiency of this process. Let the filter run until your water turns a bright shade

Method # 2: Floc your swimming pool 

Another beneficial method to clean your saltwater pool is floccing. You will need to purchase a floc or flocculant chemical that you will use in the water of your pool. This chemical will push the algae to the bottom of the pool. From there, you will have to vacuum them to get rid of them completely. Keep in mind not to use this method if your pool has a cartridge filter because it can get clogged severely. Here are the steps that you need to follow!

  • Turn your filter on in the recirculate mode

By doing so, the water in your pool will move in circles. This mode allows the floc chemical to mix better. There should be no water getting through your filter during this method.

  • Add the flocculant

Each flocculant product will come with proper instructions that you should follow. So, you are not left guessing how much of it you will have to use. You can find flocculants in both powder and liquid form. And you have to add as much as the instructions recommend, according to your pool size. 

  • Let the water circulate for a minimum of two hours

It is essential to allow the flocculant to mix with the water properly. This step shouldn’t take more than two hours. All you have to do is let your filter on recirculate mode for this time. 

Once this time frame passed, you should let the chemical sit in the pool overnight. When you revisit your pool in the morning, you should find a layer of residue at the bottom of it. 

  • Vacuum your pool

Now all you have left to do is finish cleaning your pool by vacuuming it properly. You will need a manual vacuum cleaner and use it like you usually would. Set the valve of your filter on waste, so you don’t get it clogged. Unfortunately, you will not have the waste mode on a cartridge filter. This is why the floccing method doesn’t work for pools that use a cartridge filter. 

To complete this method, you can also shock your pool with acid and chlorine just to be sure that you sanitized it correctly. 

Method # 3: Pool Algaecide 

The last method to eliminate algae from your saltwater pool is by using algaecides. While this method could be quite as efficient as the previous ones, it does involve some risks.

Algaecide products can contain hydrochloric acid as well as chlorine, metals, and aluminum. So, if you don’t want to waste money when you already have acid and chlorine, the chances are that you shouldn’t invest in algaecides that contain only these chemicals. However, the metal and aluminum algaecides might be worth a try if the chlorine and acid didn’t work for your pool.

A wise way of using algaecides is by adding about 200 ml in your pool once a week. This method is more a prevention method than a cleaning method. It will stop your algae from growing inside your pool in the long term. Keep in mind that the metals in algaecides can damage the quality of your pool and stain it. So, don’t overuse these products unless you have to!

Which method is the best?

Now that you are aware of the three main methods to clean your saltwater pool, you might wonder which one is the best. The good news is that they all work, but it will be up to you to choose the one that you prefer. You can also combine these methods to get the best results. Even so, shocking the poo,l to get rid of different algae contamination seems to be the most popular method around the world. 


1. Salt Water Chlorination

An interesting fact that beginners in this field need to understand is how the saltwater chlorination works. You will add a salt amount in your pool, and the salt chlorine generator will convert this salt into a hypochlorous acid as well as sodium hypochlorite. This sodium hypochlorite is known as chlorine. 


You don’t have to worry about getting too much chlorine in your saltwater if your chlorinator works correctly. The chlorine will stay at a minimum level all day long so you can safely swim inside your pool without any risk. 


2. Test Water

Testing the water in your pool is very important if you want to know its quality at all times. You should check the saltwater in your pool once a week. If it is too high, it will damage your pool mechanism, while if it is too low, it will not maintain sanitized swimming water. The salinity level should be anywhere between 1500 ppm and 4500 ppm. Less than that will reduce the chlorine level as well and make your pool more prone to contaminate. 

How to prevent algae growth?

If you want to be one step ahead of your algae problems, there are certain things you can do to avoid algae growth.

You should consider shocking your pool at least once a week. You can do that even if you don’t see signs of algae contamination. It is an excellent method to keep these problems away.

Cleaning your pool of debris every time you need to is also essential. You will need a pool vacuum cleaner for this measure, but it is relatively easy to do. Brush the walls of your pool as well to make sure it stays clean and prevent algae growth.

Using an algaecide weekly is also an excellent prevention solution. You will just need to add a small quantity of such a product into your pool every week, and algae growth shouldn’t become an issue!


Even if Algae in saltwater pools is a bothering problem, you can keep it under control by using the tips in this guide. Do your best to prevent algae contamination, and if you can’t avoid it, treat it as soon as possible. Such an issue only gets worse in time!