i would think there's a diminishing return in this whole reusing hydroton thing. If you're using 10 gallons of hydroton in your grow, isn't that a big enough grow to support replacing the hydroton? I'm only saying because i would probably never wash that much, especially after a week of drying. When i pull my plants, i cut the roots off at the base of the net pot and then pull the stem and the rest of the roots, bash the hydroton out and the wash it. 90% of the roots come out with the plant.
I add only an inch of water to my bathtub when i do it, so they arent really floating. Then soak and move em around like that. Then fill and use collander to grab all the one that float. Then drain tub while agitating the ones on the bottom to keep most of the dirt in the draining water. Don't let pebbles down your drain; a trip from the plumber to fix that kind of a clog will have people asking questions in anythin but your own house; hope for a non mormon plumber. Then rinse the ones left in the tub with shower head and then pull em out. Then i boil them in batches in a large spagetti pot. Anything left on there is sterile, and since i use h202 in my res i don't find mold or rot to be an issue at all.
If i had a bigger grow, id just replace rather then reuse. On the other hand, i know that the level of sterility many people work for is not neccessary because my grow works and im no were near as careful. I would always advise maximum sterilirty of course lol.