A couple more questions about sm90 for Issack or anyone else who has used it. I seen someone say sm90 messed up the calibration of their pH meter. Is this true and has an one else experienced this? Also after this barrel of soup runs out I plan on not running the sm90 again unless needed. Ive heard it leaves behind an oily residue, is this true? Is there anything I should or shouldn't use to clean out my barrel before refilling it?