Mustard algae is one of the most common problems that can occur when you have a swimming pool.
This type of algae will grow on your pool walls and floors, as well as other surfaces around it.
If left unchecked, this algae could ruin your pool’s appearance and cause health issues for your family. But there are ways to prevent it from forming in the first place!
In this article we shall look at what mustard algae is, what to do about removing it, and how to prevent it. So, without further ado, let’s get to it.
Table of Contents
What Is Mustard Algae?
Mustard algae is actually an alga (a single-celled plant) that grows naturally in water. The name comes from its bright yellow color.
You may also see it referred to as blue green algae or cyanobacteria.
It is not harmful to humans, but if it gets out of control, it can be very destructive. In fact, it has been known to kill fish and even small animals like frogs.
It is best to remove this algae before it starts growing and causes any damage. Here are some signs that you should take note of:
- Yellowish-green stains on the surface of your pool or spa
- A foul smell coming from your pool or spa
How To Remove Mustard Algae From Your Pool
The first thing you need to know is that you cannot just use chlorine bleach to clean up a musty smelling pool.
Chlorine bleaches are great for killing bacteria, so they are perfect for keeping your pool clean.
However, they won’t help with the odor problem. That’s because chlorine does not react with organic compounds; it only reacts with inorganic ones.
So, the next step is to use a product specifically designed to eliminate odors.
There are many different types available, including those made by companies like Swimming Pool Solutions.
They contain enzymes that break down the organic matter that leads to the unpleasant smell.
Once you’ve removed all the visible algae, you’ll want to make sure that you’re taking steps to prevent it from returning.
If you don’t, then you’ll quickly find yourself dealing with more than just a few spots of mustard algae.
You’ll also want to keep an eye out for any new growth. If you notice any, you’ll want to act fast to stop it before it spreads.
How To Clean A Swimming Pool With An Algae Outbreak
There are two main methods used to treat pools with algae outbreaks. One involves using chemicals, while the other uses heat.
Let’s start with the chemical method.
Chemical Method
This involves treating the affected area with a special solution containing hydrogen peroxide. Hydrogen peroxide is a compound that breaks down organic matter.
This process is called oxidation. When applied properly, it can effectively deal with the algae. However, it can also cause severe damage to your pool equipment.
That’s why it’s important to follow the instructions carefully. For example, you shouldn’t apply it directly to the filter.
Instead, you should spray it onto the sides of the filter. This allows it to soak into the material and slowly work its way through the system.
If you have a swimming pool heater, you can also try applying the treatment to the heating element. Again, you should spray it on the side of the unit.
When you finish spraying, wait approximately 30 minutes. Then turn off the heater and let it sit overnight.
The following day, check the filter again. If there are still algae spots, repeat the process.
Another option is to use a commercial pool cleaner. These products contain powerful oxidizers that can get rid of the algae without causing too much damage.
These cleaners usually come in concentrated form. You simply add water to them and mix well. They may even include a pump.
Then, you simply spray the solution onto the affected areas. Wait about 10 minutes and then rinse thoroughly.
While this method isn’t as effective as the others, it’s probably the easiest one to perform.
Using Heat
The second method involves using heat. This involves placing a small amount of salt in the affected area. Salt has been shown to be very effective at killing algae.
However, it doesn’t always kill everything. So, if you see any greenish-colored patches after adding the salt, you’ll need to repeat the process.
The best time to do so is when the sun is shining brightly outside. That way, you won’t have to worry about damaging the surface.
Again, you’ll want to wait until the salt has completely dissolved. Once it does, you’ll want to rinse it away.
Now, you’ll want to dry the entire area.
Finally, you’ll want to apply some kind of sealant. This will help protect the surface from future algae outbreaks.
Preventing Mustard Algae

While there are no foolproof methods for preventing this algae from reoccurring, there are things that you can do to reduce the chances of it happening again.
First off, you’ll want to ensure that your pool is properly maintained.
Regular maintenance includes testing the pH level, checking the filter, and cleaning the skimmer basket.
These are all important steps that you’ll want to perform regularly to keep your pool looking good.
Next, you’ll want to avoid adding too much salt to your pool. Saltwater pools are prone to developing algae due to their high levels of dissolved minerals.
Adding too much salt can lead to an imbalance in the pH level of your water. This will result in the formation of algae.
Also, try to maintain a balance between the amount of sunlight and shade that your pool receives. Too much sun exposure will encourage the development of algae.
On the other hand, too little light will cause your pool to become cloudy.
If you have a lot of leaves floating around in your pool, you might want to consider using a leaf vacuum.
Leaf vacuums work well at removing debris from your pool, which will help prevent the buildup of algae.
Finally, you may want to invest in an automatic pool cleaner (see also ‘Best Dolphin Pool Cleaners: Reviews & Buying Guide‘). This type of device will automatically clean your pool without requiring you to get involved.
You can set it to run every day, weekly, or monthly depending on how often you plan on swimming.
There are many ways to remove mustard algae from your pool. The best way to determine what works best for you is to experiment.
Start small and see if you can get rid of the algae completely. Then, once you’ve found something that works, you can scale back as needed.
Using A Pool Cover To Avoid Mustard Algae
A cover over your pool can be used to protect against algae. Some covers come with built-in filtration systems, while others require you to install one separately.
The main advantage of having a cover installed over your pool is that it protects your pool from rain and snowfall.
When these elements fall onto your pool, they can damage the surface. A cover prevents them from getting into the pool.
Another benefit of installing a cover is that it helps to keep your pool cooler during summer months. Since the cover blocks the sunlight, it keeps the heat inside the pool.
However, not all types of covers are created equal. For instance, some covers are made from vinyl, while others are made from plastic.
Vinyl tends to hold up better than plastic when exposed to the elements.
Depending on where you live, you might need to use different materials to make your cover.
For example, if you’re located in a coastal area, you’ll likely need to use a material that’s resistant to saltwater.
If you live near a lake, you’ll probably need to look for a material designed specifically for lakes.
You should also take care when choosing your cover. Make sure that it fits tightly over your pool so that no air gets trapped underneath.
Also, make sure that there aren’t any sharp edges that could cut through your skin.
You should always test out your cover before putting it in place. Use a hose to spray water on the underside of the cover to ensure that it won’t leak.
Do You Need To Remove Pool Toys If The Swimming Pool Has Mustard Algae In It?
Pool toys are great fun for kids and adults alike. However, if your pool has a thick layer of algae growing on its bottom, you might want to think twice about adding new toys.
Algae thrives on surfaces that are wet. As such, if you add anything to your pool that creates more moisture, you’ll increase the likelihood of algae growth.
If you notice that your pool has a large amount of algae growing on its floor, you should first try to reduce the amount of moisture in the pool.
Next, you should consider removing any items that create additional moisture.
For example, you shouldn’t put toys in the pool unless they have been thoroughly cleaned.
In addition, you shouldn’t leave towels or other objects lying around in the pool. These things will collect excess moisture.
Once you’ve removed everything from your pool that causes extra moisture, you should start looking at how to prevent future algae growth.
This includes cleaning the pool regularly to kill off existing algae.
In addition, you should clean the filter system regularly to remove any debris that may cause algae to grow.
Finally, you should check the pH level of your pool every few weeks to ensure that it stays within acceptable limits.
Final Thoughts
Whilst a mustard algae outbreak is never fun, it can be treated and prevented. By following the tips above, hopefully any outbreaks will be few and far between.
Because of that, you can enjoy a clean pool that will stay healthy for you and your family and friends to use all summer.
Thank you for reading!