The best preventative is using an algaecide as part of your routine maintenance program. While continuous chlorination and shock treatments help to control algae, they may not be completely effective. Applying an algaecide on a regular basis is the way to go.

Algae are tiny microscopic plants that enter your pool by rain, wind and fill water. If allowed to grow unchecked, your water will quickly become unusable. One ounce of water can contain millions of algae cells before they are visible. They can clog filters, and reduce water circulation and effectiveness of pool chemicals.