Perhaps you're using the wrong type of wood. I have had driftwood in my tanks for years and never encountered the problem you have. I usually find my own in local lakes and rivers.
Your plecos may be the source of the detritus. Many of them rasp on wood and the fibers end up in their feces. Over time they can whittle the wood down to nothing.vancat said:I really like it- and so do the plecos & shrimp.