I have been given a 135gallon tank 72x24x18h. It belonged to a friend of mine and it was all cut apart. It still has the old silicone on the edges and panes. I can use a razor blade and get the majority but still some stays on the glass. I can't seem to get it off. I know nothing dissolves silicone, so what do I do? I tried a wire wheel on a drill that gets it but scratches the glass. It will be used as a refugium,...so any suggestions?