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How to determine which pool algaecide and pool clarifier is best for your swimming pool
Add preventative algaecide to your swimming pool on a weekly basis if you regularly experience problems with algae growth.
If you have never had an algae problem in your swimming pool, there is no need for the algaecide.
Realize that if you have algae right now, you may need to use an algaecide.
Some algaecides are preventative and others are used to treat an algae problem. Once algae has grown in your swimming pool, only a treatment algaecide combined with shocking will kill the algae.