After a rainstorm, airborne algae and dust gets washed into the pool. Couple this with warm water and sunshine and it’s a perfect growing environment for algae.

If the algae load is suddenly increased, the mineral ions responsible for eradicating the algae are over-whelmed and outnumbered and cannot keep up with the accelerated growth of algae.

Once algae starts and the pool turns green, you must use super kill algaecide and then shock the pool to clear it up. Also, make sure the pH, alkalinity and phosphates are in the optimum range.

To prevent this problem from occurring, there are several options:

1) Keep the copper ion level at 0.3ppm to 0.4ppm. This concentration can help keep algae from taking a foothold.

2) When it calls for rain, add some algaecide to the water to boost the action of the minerals.

3)  Shock the pool with a chlorine or non-chlorine super oxidizer more often during hot weather and during rainy weather. This will help control the proteins that the algae feed on and will kill residual algae.

4) Add an additional chlorine puck to the pool if the weather is hot or if there is heavy usage of the pool.