I'm fairly certain that this is a bad idea, but there is a reason behind it. My 90 gallon has half of its top under plate glass that is built into the tank are part of the bracing, I guess. That glass is nuking my PAR levels for everything under it. I'd like to cut holes in that bracing. I THINK cutting glass while it's under an undetermined amount of stress is a bad idea, but I'm thinking I can apply clamps to the glass to relieve that lateral stress and allow us to do the work. I am not sure though, and that's why I'm posting in here. I need some science to work with, so can someone who really knows glass help me out? The glass is all non-tempered.