Algae create a chlorine demand in the water for itself, consuming chlorine that should be working on other contaminants. As it expels carbon dioxide, the pH level of pool water can rise.

Does algae kill chlorine?

Chlorine. … Chlorine is the only chemical that acually kills algae. It acts in the same way as setting fire to the algae, it oxidises it. When you have a bloom of green algae in your pool then by far the best thing to do it to blast it with a shock dose of unstabilised chlorine.

Can algae grow in chlorinated water?

Lower chlorine levels can lead to faster algae growth. This is because low or inconsistent chlorine levels contribute to poor water sanitation. Poor water sanitation is a factor that can lead to algae growth.