The Seachem Algae Scraper Is Suitable For Both Glass And Acrylic Aquariums And Has Three Retractable Blades Made Of Metal, Plastic, And Soft Padding. It Is Portable And Has An Ergonomic Grip That Is Cozy To Grasp In Various Postures. It Also Floats For Simple Retrieval. Finally, Because Of Its White Appearance, It Is Simple To See The Algae You Wish To Remove And When You Have Successfully Done So. Metal Removes Stubborn Algae With Ease From Glass Aquariums Use Not Recommended With Acrylic Plastic Safe For Use On Acrylic And Glass To Prevent Scratching Acrylic, Take Caution Around The Gravel Line. Supple Pad Aquariums Made Of Acrylic Are The Best Option. Algae Is Easily Removed From Scratches.