Depending on what type of algae you're scraping, razors can be very useful. If it's just brown algae, plenty of things will eat that readily. However, considering you're saying how difficult it is to remove, I'm wondering if you have something like "green dot algae". This nasty stuff, literally a horde of tiny green dots, binds to the glass like concrete, and when I've dealt with tanks that have it, a razor is the only way to remove it. For this, Ace Hardware sells a handy little plastic scraper handle that holds a single razor blade, and it's only 2 or 3 bucks.
Kurt A. Zahringer
The Eclectic Aquarist
(I like the ring of this better)