Algaecide

Algaecide is a helper, not a fix. Chlorine does the main job of killing algae. An algaecide adds a second layer and can slow regrowth between visits.

If your pool turns green, adding algaecide alone will not clear it. You need to brush, filter, and bring free chlorine back up first. Pick a product that fits your pool, such as one that does not foam or stain, and follow the label. Some copper-based types can stain surfaces, see metal stain. If algae keeps returning, ask for a full water test.