So I want to try to remove some of the scratches from my tank. I want to use cerium oxide to try that but from what I have seen and heard there are different grits. I know that some of you have had experience with cerium oxide and I need your opinions and experience. Most of my scratches are visible but cannot be felt. I do have some that you can feel with your fingernail but your nail does not fall into the scratch. Please help!