I wanted to bring up another bug. I had a huge infestation of these things in my last tank and no matter how I described it everyone kept saying 'planaria' even though I KNEW it wasn't planaria. I search for a couple of months and couldn't find anything and wound up breaking down the tank and starting a new one. AFTER I did that, I was looking up another bug and FINALLY found what I had had in the last tank. It's called Rhabdocoela. I did a search in this thread and didn't find any matches so I'm going to guess it hadn't been brought up. These are flat, white worms but they lack the triangle head or eyes planaria has. They climb up the tank walls, go through the substrate, etc. So for those folks who have flat white worms and know they aren't planaria but don't know what they are, they could be these Here's a photo. If you do a Google search you'll hit a good thread on Shrimpnow that goes through the differences between them and planaria.