Algaecide is an effective tool in preventing and treating the yellow, green and black algae in swimming pools. However, excess amounts of the chemical are harmful and must be addressed.
Watch for the signs
Foaming or cloudiness of the water surface, and eye and skin irritation are signs of too much algaecide. Check the product label to find the proper dosage that corresponds with your pool's capacity if you aren't sure.
Let the chemical naturally dissipate over time
Wait for the concentration of algaecide to decrease due to evaporation, splash-out and backwash.
Drain some of the water
If skin and eye irritation is severe, or you do not want to wait for the chemical to go away on its own, partially drain the pool, and add fresh water to correct the problem.