Question on cleanup of used reef tank

Hi, everyone.
I recently purchased a used 65 gal reef tank.
I am planning to reuse it but it has been in storage for almost a year
in a "dirty" condition.
I wanted to know what is the best way to remove the old pink / purple
algae from the aquarium before setting it back up.
I am a little leery about doing too much scraping with a razor blade for
fear of scratching the glass.
Thanks for all input.
Chris