The algae scraper is basically a required tool for any aquarium, especially coralline rich saltwater tanks. The glass (or acrylic) we look through quickly becomes dirty and full of stuff blocking our view. Some hobbyists have magnetic algae scrapers, which are a great general purpose device. However, the stubborn algae needs a little more convincing. In steps the metal tipped algae scrapers (or hard plastic tipped for acrylic tanks). The overzealous aquarium keeper goes to town, getting every purple crusty flake from the glass. But if the scraper gets too close to the edge, it will chew through the silicone holding the tank together and keeping water from spilling out onto your floor. The moral of the story, when scraping the algae off the glass, be careful. Otherwise you might not have a functional aquarium to scrape algae out of.