AquaTech Algae MagnetEasy way to keep your aquarium clean and free of algae. Coarse surface goes inside aquarium and is easily moved with external magnet. Get into small spaces that are hard to reach with handle scrappers. Easy to clean and durable. Attachaed string on in tank part makes it easy to retrieve without getting hands wet.Directions: Separate Magnets. Attach String to Loop On Each Magnet. Important: Before Attachment, Make Sure String Length Is Slightly Longer Than The Measured Height of Your Aquarium. Position The Yellow Contact Magnet On The Inside of Aquarium & and The Green Felt Contact Surface Magnet On The Outside. Magnets Will Bond Through Glass. Slide Outside Magnet Over Glass to Remove Algae Spots. After Use, Rinse Yellow Magnet Thoroughly. Note: If Inside Magnet Detaches & Falls to The Bottom, Use The Attached String to Lift Magnet to Surface