I collect my own driftwood and have never had any problems with simply just power washing the pieces. If they were previously in the water I let them dry out completely for a few days. I then just power wash them to get all the loose debris off, sometimes using a scotch pad as well. The pieces will most likely float if you use this method, however the large piece I have in my tank just now sank after being submerged for over 6 months! I wasn't willing to wait that long before placing it in my tank!