The variety of algaecides on the market can become confusing. Some have percentages, while others do not. Some contain copper sulfate, while others do not. Below is a basic breakdown of the differences between your algaecide options.
Algaecides that come labelled with a percentage are organic-based algaecides. These products become more concentrated as the percentage increases. For example, a 40% algaecide is less aggressive than a 60% algaecide.
Percentage algaecides, however, should generally not be used in conjunction with a chlorine shock. The chlorine actually damages the algaecide’s organic elements, making it less effective. As a result, algaecides that are labelled with a percentage are best used as a preventative or maintenance treatment.
Synthetic algaecides do not have a percentage attached to them and can be used alongside an aggressive chlorine shock. These products can be used for maintenance, but they truly shine as algae-removal treatments.
Two common variations of synthetic algaecides are those that contain copper-sulfate and those that do not contain copper-sulfate. Copper-sulfate is a highly-effective algae killer, making algaecides that contain the chemical very powerful. Unfortunately, some pools tend to have high copper levels, and adding more copper to the water in such cases can be a bad idea.
For pools that already have high copper levels, avoiding copper-sulfate-based algaecides is usually best. Keeping metal levels low will help to prevent staining and scaling. Copper can also sometimes turn light-coloured hair green.