You can also use a buffer ball on a drill to get in tight spots. you should sand the tank before using Novus 1,2,3, make sure you wet sand and use a palm sander, start off with 1000 grit sandpaper then use 2000 grit. The trick is go in one direction with the 1000 grit then different direction with 2000 grit ( horizontal then vertical ) you will get out most of the scratches and the ones that are to deep you can fill in with super glue. Make sure when you use the Novus after each step you wipe the acrylic good before going onto the next step.