I use a Mag•Float w/scraper on the inside(of course) and Kent Acrylic/Glass Cleaner Polisher. After using the Kent spray I noticed the touch of the Starfire glass is super smooth and stays clean longer. I thought is was the same as computer screen cleaner, which I also have, but it has something that doesn't leave any trace but for a very smooth feel.
The largest Mag•Float has a scraper on one end that extends the reach without the magnet being so close that it attracts sand.
I've been using this setup since last summer with no problems/scratches.