Abstract: Compositions for removing scale and/or inhibiting formation thereof include an alkaline agent, a primary scale inhibitor, a secondary scale inhibitor and a solvent. The primary scale inhibitor may include phosphonic acid, salts of phosphonic acids and combinations thereof. Suitable secondary scale inhibitor may include aminocarboxylic acids, salts of aminocarboxylic acids, carboxylic acids, salts of carboxylic acids, polycarboxylic acids, salts of polycarboxylic acids, gluconic acids, salts of gluconic acids, steroids, tetrapyrrols, ionophores, 2,2?-bipyridine, dimercaptopropanol, ortho-phenanthroline and combinations thereof. The compositions may be prepared as a stable concentrates that have pH values greater than or equal to 11. The compositions may also be prepared on site as a use solution. Methods of using the compositions to extend system operating times and to remove scale from and/or inhibit formation of scale on an article are also disclosed.