When scraping the algae off of the walls of your aquarium with a magnetic scraper, don’t get too carried away and knock the magnet off. Even though most magnetic scrapers are more than capable of sticking to the walls of your tank, the violent back and forth movement to get that difficult coralline algae can send the internal half flying. For floating magnets, this isn’t much of a cause for concern because it will shoot straight to the top of the aquarium. Scrapers with non-buoyant parts are far more dangerous, as they can be sent flying into nearby corals or sessile invertebrates. If not corals, then the sinking part could land in sand and catch grains in its scrubbing pads, potentially causing scratches in the glass or acrylic when cleaning.