Tips for keeping algae out of your pool
Let’s start right at the most basic level by examining, “What is algae?”
There are over 21,000 known types of algae that are grouped into 7 different categories by microbiologists. There are 4 main groups that can grow in pool water: red algae, black algae, green algae and yellow algae. These plants thrive in a pH between 6.5 and 8.5, so the goal is to make your pool environment inhospitable for them.
Here are a couple of definitions to help you better understand ways of dealing with pool-based algae.
Algacide (also spelled algicide)—a chemical agent added to water to destroy algae.
Algaestat (also spelled algistat)—a chemical agent added to water to prevent algae.
In addition, some chemicals can act as either an algaecide or an algaestat, with different dosages depending upon how the chemical is being used.
The Most Popular Algaecide on the Market
Traditional pool chlorine is the most popular algaecide on the market; it kills and prevents algae as long as the level remains consistently above 1ppm. That’s where it becomes tricky—there are so many demands placed on the sanitizer that by the time it is supposed to act as an algaecide it is “worn out.”
One of the best ways to prevent algae in the first place is to use a good preventative algaecide on a weekly basis. This way, the chlorine can concentrate on sanitizing and the algae can fight the formation of algae. We recommend Club Pro Algae Kill.
Keep Your Pool Circulating Properly
Proper circulation of the water in your pool is equally important so that the sanitizer moves throughout the entire pool. A 1-ppm concentration is enough to prevent algae–but only if that 1-ppm comes in contact with every part of the pool. Even with good chlorine residual, algae can still grow in areas of poor circulation (near steps, swimout platforms, ladders or around liner seams). For example, if you only run your equipment 2 hours a day during the summer, it’s a good bet your pool will start to grow algae. This has to do with both sanitizer circulation and algae that is trapped in the filter. Many types of algae float or have been brushed from the walls of the pool. Once algae is trapped in the filter, it will be killed by the sanitizer-laden water passing through the filter.
Algae is a plant that has roots that help it easily attach to the irregular surface of plaster and the grain in vinyl. Vigorous brushing with an appropriate pool brush literally tears the algae off by the roots. It also breaks the “protective shield” that algae grows around itself, thereby allowing sanitizer and algaecide to penetrate the outer membrane and literally “burn” its insides.
Many people mistakenly think that algae is becoming more difficult to kill because chlorine and bromine have somehow become weaker. In reality, various strains of algae have adapted to typical amounts of sanitizers and it takes more to kill them.
Swimming pool algae should never appear if all of the preventative factors are present.

  • Circulation
  • Filtration
  • Brushing
  • Sanitizer

These are your keys to keeping your pool algae-free all summer long. At Pettis Pools & Patio, we are always happy to answer any questions you may have. Feel free to stop in and get personalized recommendations on how to keep your pool algae free!
We’ll be following up this post with another algae-focused blog post later in the week that talks about how to get rid of algae if it appears in your pool.