This variety of yellow-green algae, formally known as Chrysophyta, finds its way into pool waters through multiple avenues, from airborne pollen to waterfowl and even unwashed bathing suits. When allowed to proliferate, mustard algae can turn a pristine pool into an unsightly, yellow-tinted water body, which could be mistaken for a sand-filled pool by an untrained eye.
Mustard algae infestations can be managed efficiently with the right equipment and approach. Several key products can aid in this endeavor – anti-algae agents, chlorine granulate or liquid chlorine for shock chlorination, chlorine tablets, a pool floater, pool test strips, a pool brush along with a telescopic rod, and last but not least, safety glasses and plastic gloves.
There are three main facets to tackling a mustard algae problem.
- Identifying the Algae: Recognizing the yellow-green coating in the pool is the first step. Mustard algae often resembles sand in the pool, leading to misidentification, especially among beginners.
- Understanding the Formation: Mustard algae can enter the pool through several channels such as pollen, waterfowl, or even through humans who have previously bathed in a freshwater body. Inadequate water treatment can accelerate the formation of a yellow coating in the pool.
- Elimination: The process of eliminating mustard algae involves the utilization of specialized products, a diligent cleaning regimen, and maintaining optimal water parameters. This includes pH levels between 7.2 and 7.6, alkalinity values between 80 and 120 ppm, and calcium hardness at a value of 200 to 400 ppm.
In dealing with mustard algae, it’s essential to use certified products and avoid home remedies. The process starts with brushing the pool, running the pool pump, scrubbing the pool again, and continuously controlling the pool water. In severe infestations, tougher steps are required, which include checking the circulation time in your pool, carrying out a pool shock, thorough scrubbing, and the use of an algaecide.
How Are Yellow Algae Formed In Your Pool?
The mustard algae can find its way into the pool in several ways.
It is possible that the yellow algae landed in the pool water through pollen or ducks.
But humans themselves can also have brought in the yellow algae.
This usually happens when you have bathed in a piece of fresh water and go back into the pool with your unwashed clothes.
If the water treatment is still inadequate, it is a matter of time before a yellow coating forms in the pool.
I explained in detail in the article how to remove the yellow mustard algae.
How To Recognize Mustard Algae In The Pool?
Mustard algae belong to the yellow algae (Chrysophyta) group and can be recognized as a yellow-green coating in the pool. It is likely mustard algae if you find yellow buildup in the pool.
The mustard algae are often mistakenly mistaken for sand in the pool by beginners.
Shock chlorination must occur at the latest when large areas of yellow spots in the pool or yellow water in the pool are visible.
What Do You Need To Get Rid Of Mustard Algae In Your Pool?
In addition to the green algae, the mustard algae are relatively easy to remove from your pool, but certain pool equipment is still required for a successful cleaning.
You need this seven products when cleaning your pool against mustard algae.
- An Agent that is used specifically against algae.
- Chlorine granulate or liquid chlorine for shock chlorination.
- Chlorine tablets to produce free chlorine.
- A Pool Floater to dose the chlorine tablets.
- Pool test strips for general water treatment.
- A classic pool brush and a telescopic rod.
- Safety glasses and plastic gloves.
Avoid advice that swears by home remedies and only use certified products to clean your pool. Do you have it all together? Then you can get down to the business.
First, I will explain how you can remove a light mustard algae infestation in the pool. This chapter is ideal if you don’t want to use chlorine unnecessarily.
Is your pool contaminated over a large area? Then jump straight to the chapter on how to proceed if the mustard algae repeatedly appear in your pool. Here, tough measures are carried out that promise a high guarantee of success. Of course, you can also jump straight to this chapter to ensure that the mustard algae will be completely eliminated.
1. Brush The Pool
It is also important to brush your pool thoroughly to get rid of the mustard algae. Use a sturdy pool brush and sponge on the difficult spots.
I recommend a steel brush for a concrete pool – unsuitable for PVC pools.
To be safe, it is best to brush the entire basin and not just the visible areas.
The infestation of yellow algae (mustard algae) in your pool can be more advanced than you initially assumed.
To remove the mustard algae in your pool and to avoid repeated occurrences, I recommend brushing your pool thoroughly on the first run.
2. Run The Pool Pump
After all visible areas and your pool have been cleaned over a large area with the pool brush, the filter pump can be started. However, you should first measure the water quality in your pool with a water tester.
After all, scrubbing the yellow algae and filtering is only beneficial if your three pool parameters are right. Optimize the water parameters in your pool as follow.
- The pH level should be between 7.2 and 7.6
- The alkalinity has a value between 80 and 120 ppm
- The calcium hardness is optimal at a value of 200 to 400 ppm
Then let the pump run for a few hours until the water clears again.
But we’re not done fighting the mustard algae yet – The next step is scrubbing again.
3. Scrub The Pool Again
If the pool is slightly soiled by mustard algae, it is unnecessary to scrub it again. Nevertheless, I recommend scrubbing the pool twice over a large area while the pump runs.
Algae form cell walls, and scrubbing damages these walls. This increases the effectiveness of the disinfectants used.
This process ensures that you remove all algae in the swimming pool.
In the worst case, the procedure has to be repeated, creating additional costs and wasting time.
4. Continue To Control The Pool Water
After the water becomes clear again, you should check the water quality and, if necessary, improve it with a pH plus or a pH decreaser.
I recommend continuously producing free chlorine in the water for a repeated appearance of yellow algae in a pool. A pool floater with the appropriate chlorine tablets is suitable for this purpose.
Also, ensure that the water quality is right, the pool pump runs long enough, and that the surface in the pool is brushed regularly.
You have successfully removed the mustard algae from your pool.
Tip: In the article, you will find preventive measures against mustard algae further down.
What To Do If Mustard Algae Return To Your Pool?
Yellow algae can develop in your pool, even with proper water treatment. The yellow algae were not completely removed during the first run, and mustard algae can be found again in your pool after a short time.
Here, tough steps are required to permanently remove the golden algae from your pool.
This procedure suits everyone who wants to eliminate 100% of the yellow algae in the first run and prevent them from recurring.
1. Check The Circulation Time In Your Pool
One of the most common reasons mustard algae cause yellow deposits in your pool is too short a circulation time for the water.
So before we continue with the tough measures, check the pool pump’s running times. 6 to 8 hours a day is good – you can read more about the topic in the blog under the link.
The pump’s running time can easily be calculated using the following formula.
Pump running time in hours = (2 x water volume of the pool in m³) / pump flow rate in m³ / h.
Also, check whether the filter sand is clumped and may need to be replaced.
As a rule, the filter sand should be replaced every 1 to 2 years.
My tip: You can easily loosen soft lumps in the sand filter system with a suitable calcifying agent.
2. Carry Out A Pool Shock Against Mustard Algae On The Ground
Are the yellow algae mostly only found on the pool floor? If so, the first thing to do is turn off your pool pump.
Take some chlorine granulate with a shovel and sprinkle it over a large area on the pool floor. I recommend you buy the following chlorine granules. Do not aim at individual spots in your pool, and be generous with the application.
Ideally, you should wear protective goggles and a mask, as chlorine granules are easily blown in the wind and get into the eyes and respiratory tract.
After your pool has been scattered over a large area, your pool is left to rest for 24 hours so that a chlorine cushion is built up.
The pool will be brushed, and the pump will be switched on after the time has elapsed.
3. Shock Chlorinate Your Pool In The Case Of An Extensive Infestation
But what should be done if the mustard algae nest not only on the ground but also on the walls? In this case, I advise performing a pool shock with liquid chlorine – you can find a suitable agent here.
Since liquid chlorine is always differently concentrated, adhere to the following quantities to avoid over-chlorination in the pool.
- The chlorine content of 80 g / l = uses 10 liters of liquid chlorine per 25 m³ of water.
- The chlorine content of 150 g / l = 5 liters of liquid chlorine per 25 m³ of water.
When the pool pump runs, the liquid chlorine is tipped into the flow of the return nozzles.
After using the liquid chlorine, the pump must run directly for 24 to 36 hours until the chlorine content in the pool has normalized again and is below 1.5 ppm.
Then the water should be clear again – if necessary, let the pump run a little longer.
Extra tip: Using a flocculant in your pool improves the filter performance. You can find out more in the linked article.
4. Thoroughly Scrub Your Pool Against Mustard Algae
The shock chlorination is still running, but your pool cleaning is far from over.
After the pool shock, cleaning your pool with a brush is important. Do not wait until the 24 hours are up after using the liquid chlorine.
Pick up the pool brush and scrub as hard as you can! Scrubbing your pool 2 to 3 times should be enough against the mustard algae. Alternatively, you can also use an electric pool robot against algae. Using a pool robot saves a lot of time and effort.
5. Use An Algaecide Against Mustard Algae In Your Pool
In the meantime, I recommend using an algaecide in your pool according to the manufacturer’s specifications.
The following algae remedy against yellow algae is recommended.
To increase the effectiveness of the algaecide, I recommend adding approximately 125 g of chlorine per 25 m³ of pool water, provided this value was not already reached during the shock chlorination.
If the water foams during use, this is due to the algae agent. You can prevent this by using a non-foaming algaecide.
What To Do If The Pool Shock Did Not Help Against Mustard Algae?
It can happen that despite shock chlorination (pool shock), the mustard algae are not removed, and the pool water remains cloudy.
A reader contacted me in this case and told me that the pump had been running for days and that the pool was cloudy even after the instructions.
After a brief exchange about the procedure, I strongly suspected that the water values in the pool were incorrect.
Test strips were used for testing. I then recommended using an electronic water tester and reporting the remaining values.
Interestingly, the pH was 7.27, and the total alkalinity (acid capacity) was 81 ppm and thus still in the green area – the free chlorine was also abundant in the pool.
But the cyanuric acid was too high at 106 ppm and well above the ideal range of 30 to 50 ppm – that was the problem if the pool remained green despite pool shock.
In my specialist article on cyanuric acid, I mentioned that the effect of chlorine continues to decrease if there is too much chlorine stabilizer in the water.
A partial water change had to be made in the pool to lower the cyanuric acid – how much exactly, I explain in the blog article under the link.
Then the pool was cleaned again against mustard algae using the instructions.
You see, precise measurement results brought the decisive success that saved further costs and nerves in the water treatment.
Do you have any further questions about the yellow algae in the pool? Just write me a message on my social channels.
What Preventive Measures Help Against Mustard Algae In A Swimming Pool?
Purifying water in your pool isn’t all you can do to remove mustard algae. It doesn’t even have to be necessary to remove the mustard algae.
To do this, follow these five preventive measures against mustard algae in your pool.
- Wash your swimwear: The mustard algae often get into your pool through worn swimwear in a quarry pond or lake. Therefore, you should wash your bathing suit thoroughly or swap it before bathing in your pool.
- Continuous pool maintenance: Permanent pool maintenance is essential against algae – no matter their color. Therefore, let the pump run 6 to 8 hours daily and use an algaecide.
- Test the pool water: You must continuously test the pool water parameters. Only if you know the values can suitable care products against algae be used – ideally, you use an electronic water tester for precise measurement results.
- Disinfect the pool equipment: Mustard algae can survive outside pool water for a certain period. After thoroughly scrubbing and vacuuming the pool, the pool equipment should be disinfected.
- Brush the pool regularly: The floor in the pool is not only scrubbed with a pool brush when there is heavy algae infestation. Make sure that the pool is scrubbed extensively at regular intervals.
As you can see, it’s not that much work. With appropriately good water treatment, you should get the problem with algae under control.
