Cleaning dry green algae off a tank?

[SS4Gogita]

Hi all! My brother who's a fish owner himself, found this huge tank that was used as a turtle tank (there was turtle food along with the tank) outside his place. Anyway, he gave it to me, but it's filthy and has this green algae that is a pain to remove even with a scrubber. What's the best way to get rid of the green crud?

 

[The-Wolf]

use a razor blade, but be carefull.
You don't want to cut yourself.

 

[SS4Gogita]

Wouldn't that scratch the plastic surface?

What about chemicals? I know that's dangerous to fishes, but I'll just clean it up thoroughly

 

[DJ Prem]

got to your Aquarist they normally have algae cleaners