Hanna Instruments General Purpose Cleaning Solution 500 mL HI7061LHI7061L is a general purpose cleaning solution that can be used for a variety of applications. Electrodes can become dirty from use and will produce inaccurate results even as they read correctly in a pH buffer. Hannas cleaning solutions eliminate impurities and residues that are left on electrode surfaces when immersed in samples during measurement or when stored incorrectly. Hanna suggests cleaning the bulb and junction of your electrode on a