For CD treatment nothing works better than a magnetic tape bulk eraser.
But wait! CDs are not magnetic says you. Fact is it is the inks used on the CDs that is. The most common pigments used contain ferric and ferrous oxides. They ARE magnetic.
I poo-pooed that whole thing until I tried it for myself with other listeners that had no idea what I was doing. Most common comment was why did those two CDs sound different when it was actually the same one. Every (EVERY) person heard the difference. Photons, those almost massless little critters, are easily moved by magnetic fields. That is what I did in the semiconductor industry: bending photons and ions with intense magnetic fields down the flight tube of an implanter. Real physics at work, not voodoo.