The use of algaecide to prevent or destroy algae is often recommended. Its use, however, can result in water foaming, a change in total alkalinity and pH, and an increase in TDS. Cheaper copper-based algaecides can cause water discoloration, staining of the pool walls and floor, and green hair and fingernails (see copper for more information). Algaecides that contain isolated (chelated) copper are desirable, though they tend to be quite costly. With the use of various sanitizing units available, such as the Pool Wizard, algaecides are not necessary. If you use an algaecide, follow the manufacturer's directions.