Chemical cleaning of exchangers can be tricky and often not very effective. The ability to identify a solvent for material that has fouled an exchanger will depend highly on knowing what the chemical nature of the foulant is. Carbonate scale deposits in cooling water applications can be cleaned with various acidic solutions (like citric acid), but are generally only partially effective. In many cases hydroblasting is more effective, provided it is done in a manner which does not damage the exchanger.