Magnetic Algae scraper for thick glass

[asylumdown]

Does anyone know of a brand of magnetic algae scraper that's appropriate for 5/8" thick glass? I really wanted to get something like the mag flip that has a razor on it, but I just discovered that they're only effective on glass up to 3/4" thick.

The bottom of the upper doors to my cabinet are over 6' high, so I'm going to need a ladder to scrape my glass, and it would be swell if I could find a magnetic one that meant I didn't have to do that