What does everyone use to clean the algae off of their glass? I'm looking for something that won't scratch, if there is such a thing. I have a pleco, but sometimes he doesn't get all of the algae off of the glass/plants. I'm currently using a scrub brush from Wal-Mart, it's a blue sponge with a long handle. It's soft'ish at first but after I use it, it gets rough & hard. I already have a few scratches from it.