Sand paper glued to a wood block works ok but takes a while. !
Just cut some tubing and put it over the glass edges.
You could also use the plastic 'corner' that they use for drywall. Home depot or Lowes have it in the drywall section. You can cut the extra off with scissors and just silicone it on. There is no reason why you cannot make it look exactly like the tank top rim.hmm... gives me an idea. i cant put tubes on the side corners. But im definitely going to try silicone. im going to put a lot of silicone on the edges. doesnt really matter if it turns out ugly, it's hidden anyway.
thanks for all the suggestions.