Happens to my java fern's roots too. I have mine anchored to driftwood with a very sluggish water flow (it's a betta tank) that doesn't do much to help when sediment and detrius settles on my plants. I don't think it's algae, though I think I have hair or stag algae on my java and reideckii... that stuff is SO stubborn!!! :mad2: I hate it.