For the past several weeks, I've been having terrible algae problems,couldnt shake it,the other day a friend of mine was giving me a buch of his stuff cause he's moving, and he had a screwed up twister, the scraping pad was partially removed,and there's a big hunk of metal behind it,took my twister out of the tank,and in a day the algae problem is almost gone, just thought I'd share this little discovery