Poolmaster 20178 5-Inch Aluminum-Back Swimming Pool Algae Brush with Stainless Steel Bristles, Classic Collection. Pool wall brush for cleaning gunite swimming pool walls with hard-surface finish. 5-inch straight body design, die-cast aluminum back and handle, stainless-steel bristles. Compact size for hard-to-reach places; also works great as a BBQ grill brush and BBQ tool. Please do NOT use on vinyl liners or fiberglass surfaces; for inground gunite pools or spas.