I've noticed that since I've gotten a tough brown alga growing, I've had to start using single-edged razorblades. I also follow with a toothbrush. Even the two combined don't really do that great of a job. I've got two screen and they are extremely rough, so I can see why they'd stick. It's just making it more difficult to "harvest." So, in light of that, I'm wondering what everyone else is using to get the job done so that I might find something a bit better.