I just bought a used 50g tank off of kijiji. It has a hole capable of fitting a 1/2 inch pvc. I want 2 3/4 pipes for my return and overflow. Is it relatively safe to drill over the old hole or should I plug it with a closed bulkhead and drill 2 new ones? Also the trim on the top is seemingly lose, does it add a lot of strength? If I could get away with it I'd like to make it rimless on the top! Thank you, this will be my first reef tank so expect lots of questions over the next few months. I appreciate the support.