First tip! :) I read someone had trouble with
marks from their child's bath-toys on the tub. I would try using a good baking-soda based toothpaste with a cleaning toothbrush on the
marks. If that doesn't do it, use baking soda on half a lemon or lime (be sure to puncture the half with a fork a bit, so it gets juicy).
Good luck! (LOVE this show. <3)