I assume au_lait's tongue is well in his cheek as soft grade brushes used in a circular motion....arrrgh.
I have used a Nitty Gritty some 30 years with very good results. But the drive is worn out and I have to help it turn the disc. Looking to replace so all your posts are very helpful. Clearly US is the way to go, but the Kirmuss four+ stage palaver is not for me. Neither do I trust the smug pseudoscience ladled out by Mr K.
Costly, but the Degritter looks the way to go. Computer control manages all functions automatically and makers don't stress any need for additives to plain old distilled water.