Is Red Algae in the Pool Dangerous? What You Should Know

Is Red Algae in the Pool Dangerous

Even though you’re on top of your pool water care, one day you notice that your pool water, walls, steps, jets, skimmers, and even the ladder looks slightly rust-colored. This is often referred to as red algae, pink slime, pink algae, etc., when in fact it’s not algae; it’s bacteria.

Red algae looks the way it does because of the pigment from within its cells, and the slimy substance that forms around the bacteria protects it from external threats. This type of bacteria loves to grow in the dark corners of the swimming pool or any areas that don’t receive much sunlight, and with minimal water movement.

What you’re really wondering, though, is whether red algae in the pool is dangerous to humans. While it is detrimental to our health to swim in a pool with red algae, the risk is not severe. The algae can produce toxins that cause skin irritation, redness, vomiting, nausea, and dizziness. It can even cause respiratory problems, so people with asthma beware. You should still strive to get rid of red algae as it isn’t exactly good for you either.

Since red algae is so unsightly and bad for you, we don’t want it to spread. In this article, we’ll go over how you can identify red algae, how to get rid of red algae in your pool, and ultimately how to prevent it from being a danger to your health.

Why is there red algae in my swimming pool?

Like any bacteria, red algae often comes from outside sources like rain, wind, contaminated pool accessories, and swimmers themselves. In fact, humans are often the culprit for the spread of red algae into pools. There’s a reason why swimming pools tell their guests to shower before entering the pool, and maybe you should be strict with that rule in your own pool.

Bacteria are being introduced into your pool all the time, and that is why pool maintenance is so important. If you notice red algae growing in and around the pool, that is a sign of improper water and pool maintenance, as well as poor water circulation.

Another major factor is how much sunlight your pool is exposed to in a day. Pools that receive less than 6 hours of direct sunlight a day are more likely to encounter red algae growth. Rain water that enters your pool is another source of pink algae infestation.

“But I treat my pool all the time!” you might say. So why is there still pink slime in your pool? That’s because pink algae is resistant to chlorine and bromine. Even after shocking your pool, traces of pink algae can remain on pool toys and accessories, and if you add them back into the pool without sanitizing them, another infestation might begin.

Is red algae dangerous?

Yes and no. Generally speaking, the danger red/pink algae poses is minimal. It is unlikely to cause any diseases or infections, but can cause skin irritation, redness, nausea, vomiting, dizziness, and shortness of breath.

That said, this slimy substance can coat the pool wall, ladders, the bottom of your pool, and can make these surfaces slippery. Be careful not to slip on them, because a nasty fall can indeed be very dangerous.

To be safe, it is best to err on the side of caution and remove any signs of algae growth in your pool. If you are experiencing symptoms that don’t go away on their own, then consult a doctor because you may be having a severe reaction to the pink algae.

How to get rid of red/pink algae in your pool

The best way to deal with algae is to prevent it from growing and spreading in the first place. To that end, you should implement the following steps.

  • Shower before entering. This is a solid rule that swimming pools enforce, and you should do it too. Humans are the primary reason that pink algae spreads, so by first giving yourself a rinse, you can hopefully wash off this bacteria so that it doesn’t reach your pool. Ask guests to do the same.
  • Regularly clean your pool. Don’t just rely on chemicals to do the job. You should be frequently brushing, wiping, and vacuuming your pool. While you’re at it, clean your pool accessories as well, including pool toys, floats, skimmers, baskets, and anything else you have in your pool. Use a pool cover when it rains so that rainwater doesn’t introduce the bacteria into your pool.
  • Expose your pool to sunlight. On sunny days, take off that pool cover and let your pool soak in the sunlight. Sunlight and UV rays are natural oxidizers that can prevent the spread of red algae. Also, this is a good opportunity to actually use the pool. Water that is in motion is less likely to have pink algae growth.
  • Use an algaecide. There are algaecides that specifically target red algae. Use them. Follow the instructions exactly as written.
  • Pool shocking. Despite being resistant to chlorine and bromine, red algae is not completely immune to them. Therefore, the high concentration of chemicals during a pool-shock treatment is effective at treating red algae.
  • Filter continuously for 24-hours. After shocking the pool, run the filter for a full 24 hours to ensure the peroxide and halogen levels are at a higher than normal concentration to kill any lingering pink algae.

How to prevent red algae

Thoroughly cleaning and disinfecting your pool is only half the battle. You also need to take care of the other sources that can introduce red algae into your pool. Here’s how:

  • Clean all pool toys and accessories using a mixture of equal parts bleach and water.
  • Never place anything into your pool without first sanitizing it.
  • You, your family, and your guests should take a soapy shower before entering the pool.
  • Maintain the pool’s pH (between 7.4-7.6, with 7.5 being ideal), alkalinity, and sanitizer levels in the recommended ranges.
  • Frequently vacuum and brush your pool. Don’t wait until it’s dirty.
  • Run your pump and filter for at least 8-12 hours a day all summer long.
  • On sunny days, take off the pool cover and let the sunlight shine on the pool.
  • Follow the steps in the previous section if you notice red algae growth in your pool.

Yes, that is a lot of work. But red algae in the pool can potentially be dangerous if you have sensitive skin or a compromised respiratory system. It is also generally a slipping hazard. You want to do everything in your power to ensure that red algae has no chance to spread and grow in your pool so that the pool stays safe and clean to swim in.

Photo Credit: Alisha Vargas (CC BY 2.0)