What is a one-sentence summary of the following article?
Algae spores transfer to your birdbath from objects that fall out of nearby trees and will grow at a faster rate when exposed to direct sunlight. To prevent the build up of algae, it's best to store your bird bath in a shaded area of your hard. You should also keep the bird bath away from shrubs and bird feeders to prevent contamination. This will help keep the water fresh and prevent algae growth from spreading within the birdbath. If you have the time to do so, add fresh water every day. Remove any visible algae when changing water in your birdbath. Pumps, drippers, and heaters that run on solar power or electric batteries are a good idea for a birdbath. Running water is less likely to become contaminated with algae. If your birdbath is not already equipped with such a device, purchase one at a local hardware store and follow package instructions for set up.

Summary:
Keep the bird bath in shade. Change the water daily. Use running water, if possible.