Corner overflow removal
 

I'm trying to remove the corner overflow from my aquarium but I can't get my razor blade in between the glass and overflow on the side/back of the aquarium. What would the best way to remove it? And the glass is at least 1/2"

Overflow removal
 

I have found that the blade of a tape measure works best, but even fishing line will do in a pinch.

+1. An old guitar string works well too!