Hey, I'm enjoying the build. a suggestion for dealing with your massive amounts of hydroton. you should try a vibratory polishing machine. I ran one as a kid. you don't need one large enough to hold all the material from one harvest, just one big enough to "wash" it all in the time between each harvest. I think with a slow constant flow of water and a bunch of steel pieces that will cut up the roots as it mixes until they can be washed away in the water.
here's a video showing one in their standard use which is usually deburring a machined metal product. http://www.youtube.com/watch?v=YDxiA0aZJIs&feature=player_embedded
here's a video showing one in their standard use which is usually deburring a machined metal product. http://www.youtube.com/watch?v=YDxiA0aZJIs&feature=player_embedded