Structurally supported, retractable covers from Geomembrane Technologies can help reliably control algae. They consist of a high-strength sheet of coated fabric tensioned across a low-profile aluminum arched frame that spans the tank opening. This design controls algae while providing easy access for plant operators to inspect and maintain tanks, basins and tube settlers. By blocking sunlight, a water treatment plant can reduce the amount of disinfectant chemicals required during the treatment process. Chemical reduction not only minimizes the formation of disinfectant byproducts to improve water quality, but it also yields significant cost savings. Temperature is better controlled and maintenance associated with algae cleaning is simplified. 855/484-4630; www.gticovers.com.