OSI Smooth Bark Tree Stump Aquatic Ornament The OSI Smooth Bark Tree Stump Aquatic Ornament is a realistic tree stump that enhances your aquarium decor. The smooth bark tree stumps offer shelter for aquarium inhabitants. These poly-resin aquarium decorations will not alter water parameters and will enhance the beauty of your aquarium. Features: . Offers ridges, knots, and hide-away holes . Will not affect water chemistry or clarity . Safe for freshwater or marine aquariums . Rinse each piece with clean, fresh water before introducing into the aquarium . Clean periodically to remove organic matter or algae . Scrub each with a medium bristle brush and spray with a pressure nozzle . To remove more persistent organic material or algae, soak overnight in an organic cleaner . Use a weak solution of water and chlorine-based bleach as an algaecide for final cleaning . Do not immerse in concentrations greater than 10% for longer than 2-3 minutes