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Understanding algae

How algaecides work

Quaternary ammonium compounds (quats) are positively charged and are therefore attracted to the negative charge on the cell wall of the algae. The quat’s wetting agent properties as well as this charge attraction allow it to enter the cell wall, which causes it to break. The structure of the quat makes a difference when it comes to the effectiveness of the product. Quaternary ammonium compounds have a ‘chain’ of carbons on the molecule and these carbon chains can vary in length. Through research and testing, it has been determined that biocidal activity peaks at a carbon chain length of 14.

Polymeric quat compounds work in a similar manner to ammonium chloride quats. However, because they are much larger molecules, they usually work a little slower than ammonium chloride quats.

Copper is effective at killing algae because it disrupts enzymatic activity within the cell.  If the enzymes do not function properly, the organism cannot survive.

Preventing algae growth

The physical aspect involved in pool care should be kept in mind. Proper circulation and filtration, as well as routine cleaning and vacuuming of the pool surface are very important.

Ultimately, proper maintenance is the key to keeping algae growth in check. The most important consideration is the presence of sanitizer, or even better—sanitizer and algaecide. Establish a maintenance system that includes maintaining appropriate sanitizer levels, routine oxidation and application of a preventative algaecide. Remember, algae treatments will be much less effective if the pool is unable to maintain a sanitizer residual.

The physical aspect involved in pool care should also be kept in mind. Proper circulation and filtration, as well as routine cleaning and vacuuming of the pool surface are very important—particularly brushing (as mentioned previously). Once algae are exposed, the products applied for sanitization and algae prevention are able to do their job, allowing them to work more effectively.

Using products that are PMRA or EPA registered as algaecides and always following product application directions will help ensure successful treatment and a more enjoyable pool experience for the homeowner.


Rigsby_HeadshotKaren Rigsby is the leader of technical services for BioLab, a Chemtura Company. She has been involved with the recreational side of water treatment since 2001, focusing on education, problem resolution and new product development. She began her career in the water treatment industry at BioLab as an analytical chemist in the research and development group. Prior to recreational water, Rigsby was employed by the Georgia Bureau of Investigation as a forensic chemist. Rigsby received her bachelor of science in chemistry from Georgia Tech and is a member of the Association of Pool & Spa Professionals (APSP) Recreational Water Quality Committee and a National Swimming Pool Foundation (NSPF) certified instructor.


Hansen_HeadshotZach Hansen is a new product specialist for BioLab, where he started his career working in automated controller and feeder equipment development. Over the last four years he has focused on new product commercialization and development for the company. Hansen received his bachelor of science degree in chemical engineering from Auburn University in 2004. He can be reached via e-mail at

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