The pink hue in the pool is caused by a bacterium known as Serratia marcescens. More commonly referred to as ‘pink slime,’ this organism might be more familiar than many would like to believe. The bacterium’s uncanny ability to infiltrate water bodies and adhere to surfaces leads to the formation of unsightly deposits, predominantly at the bottom of pools. The tenacity of this bacterium even extends to the water line and the pool’s pipe system, posing a challenge to routine pool maintenance.
Pink slime’s inception in pools can be traced back to a number of sources – from the surrounding environment to human interaction. The bacteria thrive in water conditions that are not diligently maintained, and adverse weather conditions only amplify their growth. Interestingly, the distinctive pink hue only surfaces after a disinfectant such as chlorine or algaecide is used. Pre-disinfection, the bacteria remain invisible, only hinting at their presence when the pool begins to feel slippery and greasy. The subsequent death of the bacteria post disinfection results in the distinctive reddish hue, and a pink-red biofilm may form a deposit in your pool.
To tackle pink slime, consider the following eight steps.
- Preemptive cleaning of the pool filter
- Treating pool water
- Shock chlorination
- Scrubbing the pool with a brush
- Vacuuming the pool
- Applying a pool algaecide
- Post treatment cleaning of the pool filter
- Testing and optimizing pool water
Contrary to popular belief, pink slime is not harmless. Classified under risk group 2 by the Biological Agents Ordinance, Serratia marcescens can cause human diseases. While widespread distribution among the population is unlikely, exposure can potentially lead to urinary tract infections, pneumonia, or sepsis. Hence, immediate removal of pink slime from pools is highly advised.
Moving forward, let’s delve deeper into the identification of pink slime and the comprehensive steps to combat this persistent bacterium.
What Is This Pink Slime In Your Pool?
That pink slime you’re seeing in your pool isn’t actually algae. It’s a bacterium known as Serratia marcescens. This sneaky little bacterium is often mistaken for algae due to its slimy texture and, of course, its pink color. In the US, we’ve even given it a nickname – pink slime. It’s not the most flattering name, but it certainly is descriptive.
You’ll typically find this pink slime lurking at the bottom of your pool, forming unsightly deposits. But don’t be fooled, it doesn’t just stick to the ground. It can also cling to the water line and even sneak into your pool’s pipe system. Crafty, isn’t it?
Now, you’re probably wondering, “How on earth did this bacteria get into my pool?” Well, there are a few ways this can happen. The bacterium could have been carried in from the surrounding environment or even introduced by a person. Yes, you heard that right. A simple splash of water can bring these bacteria into your pool.
But it’s not just about how they get in. It’s also about how they thrive. Pink slime loves to grow in pools where the water treatment is not up to scratch. Add in some adverse weather conditions, and you’ve got yourself a pink slime party.
Now, here’s the kicker. The pink coloration of this slime only appears after you’ve used a disinfectant like an algaecide or chlorine. Before that, the bacteria are invisible, only making their presence known when your pool starts to feel slippery and greasy. Yuck!
When you finally do add that disinfectant, the bacteria die off, leaving behind that distinctive reddish color. You might also find a pink-red biofilm as a deposit in your pool. And if you’ve got pink bacteria in your pool water, chances are your pool filter is also affected.
A complete pool cleaning is necessary to remove the pink algae from the pool in the long term. I will explain exactly how this works earlier in this blog article.
How To Remove Pink Slime From Your Swimming Pool?
You don’t have to despair if you see pink algae – or something that looks like white mold – in the pool. The pink algae can be removed quickly with my practical tips and little effort.
Before we start, you need to prepare the following pool equipment against pink slime in your pool.
- A pool brush to loosen the pink slime.
- Liquid chlorine for shock chlorination.
- Some of the algaecides for disinfection.
- Ideally, a simple pool vacuum.
Tip: You can find my recommendations via the links, which you can buy online.
Do you have it all together? Then you are ready for the pool cleaning part.
1. Clean The Pool Filter
If the pool filter turns pinkish, it is because the bacteria are also in the filter. To make pool cleaning as effective as possible, you must first clean the filter sand or the cartridge filter.
In the case of a sand filter system, it is sufficient to carry out a backwash with subsequent rinsing.
A slightly soiled cartridge filter can be rinsed off with a high-pressure cleaner, or the filter can be replaced if necessary.
2. The Pool Water Treatment Against Pink Slime
Next, test the pool water with test strips or an electronic water tester.
Ensure the pH value is between 7,2 and 7,6 because an exact pH value promotes pool cleaning in the next step. You can use a pH plus or a pH minus for this purpose – you can find a recommended product via the links.
Tip: Be sure to put on old clothes and, for safety, gloves when using the acids.
3. Use A Pool Shock To Get Rid Of Pink Slime In Your Pool
Professionals remove the pink biofilm from the pool with simple shock chlorination. Here you can use 1 kg of rapidly dissolving chlorine per 25 m³ of water.
In a rectangular or round pool, the volume of water is easy to calculate. But if you have a free or kidney shape, the pool’s volume needs to be roughly estimated.
Then let the pump run for 24 to 36 hours until the water clears again.
You can only go swimming in the pool again when the chlorine value is below 1.5 ppm.
Tip: It is best to perform the pool shock late afternoon or evening. The reason for this is the susceptibility of chlorine to the sun’s UV rays
4. Scrub The Pink Slime In The Pool With A Brush
While the filter pump is still running – immediately after the shock chlorination – you take a pool brush in your hand and scrub the entire pool surface.
Do not miss any spots. Otherwise, the pink algae may form in the pool. You should scrub thoroughly, especially in the corners and other difficult areas, so all bacteria are chased through the filter.
In the meantime, scrub the pool 2 or 3 times. Two is Better!
Tip: If necessary, use a small sponge to remove the biofilm from the surface.
5. Vacuum The Pool
If the filter does not completely capture the dirt on the pool floor or corners, try adjusting the nozzles. If that doesn’t help, you can vacuum the pool with a pool vacuum.
The only important thing here is to set the filter to Empty. You lose some water in the process, but this way, the biofilm and remaining pink algae do not get back into the water cycle of the pool.
Later the water level in the pool is raised with fresh water so that the pump does not suck in air.
When the pool is filled, the water values change, but that doesn’t matter because the values must be adjusted again after the shock chlorination.
6. Apply An Pool Algaecide Against The Pink Algae
The algaecide is a good means to inhibit the growth of pink algae. Add some algaecide to the pool and always observe the manufacturer’s instructions.
Please don’t overdo it, as too much of the algicide can be harmful and lead to foam in the pool.
Tip: Usually, an algae killer is not always necessary, but correctly dosed, it can contribute to improved water quality – you can find out more in my blog.
7. Clean The Pool Filter Again
Next, clean the filter again and possibly use a filter cleaner. This step ensures that no pink biofilm (bacteria) is left – after all, you don’t want to go through the whole procedure again?
8. Test And Optimize The Pool Water
The last step is to test the pool water again. As already mentioned, you can use test strips or an electronic water tester.
In the process, the following three parameters must be measured and optimized accordingly.
- pH value: 7,2 – 7,6
- Alkalinity: between 80 and 120 ppm
- Calcium: 200 to 400 ppm
How To Prevent Pink Algae In Your Pool?
Here you will find four measures to permanently prevent pink slime in your pool.
- Scrubbing the pool regularly: Make sure the pool is cleaned regularly with a pool brush. Ideally, this should take place daily. Using an electric pool cleaning robot against algae can make pool cleaning easier.
- Optimize the filter run times: Nothing promotes algae growth as much as a filter run time that is too short. The water in the pool should run through the filter 2 to 3 times a day, especially on hot days in June, and for this purpose, the pump must run for 6 to 8 hours – depending on the performance. In the case of small cartridge filters, an endurance run is even called for.
- Constantly producing free chlorine: Chlorine is a good disinfectant against pink algae. Use a dosing float and insert chlorine tablets in these. You can’t optimize the chlorine value perfectly, but you get very close to the value.
- Algaecide: The algaecide is not only there to kill algae but also serves wonderfully to inhibit algae growth. The application does not even make the pool greasy and slippery due to the biofilm. In my blog, I have explained in detail how to use the algaecide correctly.
You now know that the pool’s pink biofilm can harm your health. I also explained to you how the pink slime could be removed from the pool, but if it’s up to me, then you shouldn’t let algae develop in the pool in the first place.
Are Pink Algae Dangerous In Your Pool?
The pink algae (Serratia marcescens) are assigned to risk group 2 by the Biological Agents Ordinance and is dangerous in your pool water.
In addition, the ordinance and the technical rules for biological agents stipulate that these bacteria can cause human diseases.
The bacterium is negligently described as harmless in alleged pool maintenance guides, although scientific studies have shown otherwise.
Widespread distribution in the population is rather unlikely, but the following symptoms of illness due to the pink algae in pool water may still occur.
- An infection of the urinary tract
- Pneumonia
- Sepsis
Therefore, you should remove the pink algae from the pool as soon as possible.
Don’t wait until you see a biofilm in the pool.
For this purpose, I list a few preventive measures against pink slime – read on in the following chapter.
Do you have any further questions about algae in your pool? I recommend you browse my helpful blog or contact me on social media – I’ll be happy to help you personally.
