Killing Green Algae with Chlorine. Use chlorine as your go-to algae killer. ... "Shocking" the pool with a large dose of chlorine is the most effective way to kill the existing algae and bring your pool back to sanitary conditions. This usually works within 1–3 days, but can take up to a week if pool conditions are poor.

How long does it take for pool shock to kill algae?

Keep your pump and filter running. Give the shock a good 12 to 24 hours to work it's magic. If the algae hasn't cleared up after 24-48 hours, clean and brush the pool and add another shock treatment.

Does pool shock eliminate algae?

Getting Rid of Algae with Chlorine Shock

When you maintain a swimming pool with 3ppm (parts per million) of chlorine, it will inhibit algae from growing. However, if you let the chlorine drop, even for a day, you might be left with an algae outbreak, which can turn your water green.