TraceBucked

I was gifted a 30 gallon hex shaped tank, with bad seals. I am attempting to take it apart so I can re-seal the entire thing but I'm running into a problem. The top (and bottom) plastic pieces of the tank are not coming off. I've tried a razor, a putty knife/hammer and even silicone solvent, but I can't seem to make it budge. I think there is silicone on the top edge of the tank that it holding the plastic piece on but I can't seem to get to it, any ideas?