Yeah, I was thinking the same thing used (used hydroton). A good way I learned to clean new hydroton pebbles is to take an old 5 gal plastic bocket or tote, cut a hole in it w/ a hole saw on the bottom big enough for one of your net pots to fit into. Prop it up on something like a cinder block or something and run the hose on it. The dust and grit will wash down to the bottom as the water drains thru the net pot.