Hydra Aquatics Sparkly Sponge PLUS 2-in-1 Cleaning Sponge – 6 pack – Smooth side for removing algae – Abrasive side for removing stubborn algae and calcium deposits – High quality double density material – Cut it to use with tweezers – Removes algae, calcium deposits and water stains Hydra Aquatics’ Sparkly Sponge PLUS 2-in-1 Cleaning sponge has the same great feature as the original Sparkly Sponge with a smooth side for removing algae, but also has an added benefit of an abrasive side for removing stubborn algae and calcium deposits. You can cut it and use it with tweezers to get to the smaller places in your tank.