In South Carolina, you're not often going to have a pool be cool in August. There are several things you can do:

1. Make sure the surface is BRIGHT white. Any colorant in the finish will add several degrees. A dark color can add 7 - 10 degrees.
2. A spray type fountain used at night. SC is humid at night, so you're not going get lots of evaporative cooling -- you'd need a fairly high volume, going more than 2 or 3' in the air, to be effective.
3. Solar HEATING panels, with controls that allow them to be enabled at NIGHT, between 3 & 7am.
4. A deeper pool.