The translucent/gray/white fungus that grows on newly added driftwood is completely natural and harmless. You will do more harm by adding unnecessary chemicals (medication) to your tank than you would by adding the fungus covered driftwood. Plecos, nerite snails and amano shrimp devour that stuff. As a matter of fact I personally float new driftwood to my amano shrimp tank in order for them to have a feast every now and then. IF you absolutely hate it, take it out, scrub it off and put it back, you may have to do this several times for it to all come out. Otherwise leave it, its not harming anything.