Hydra Aquatic’s Sparkly Sponge is a highly durable cleaning sponge suitable for both glass and acrylic.  The micro abrasive surface allows maximum algae cleaning with minimal effort, even on scratched surfaces.  The chemically inert sponge does not add soaps or detergents to the tank, and the stark white color allows the user to visualize when all the algae has been removed. This sponge is more than twice as think as competing sponges currently on the market.  This gives it more cleaning power, and a higher effectiveness.  It can even remove stubborn algae, calcium deposits, and hard water stains! It comes in a single pack, an 8 pack display unit, and an 8 pack refill.     https://sevenports.com/product/sparkly-sponge-1-pk/ https://sevenports.com/product/sparkly-sponge-display-unit/ https://sevenports.com/product/sparkly-sponge-8-pk/