Got your attention ? I know that people advocate putting steel screws under or in the substrate to provide iron for the plants to take up. I have this BEAUTIFUL piece of hardkool from the lowveld but it has a screw protruding from it, ( my fault I used it as an ornament previously ). Can I use this as decoration ? Will the exposed screw be harmful to the fish not in a physical way - I will cut it off level to the wood ? I've heard that in marines its a BIG NO NO.