Well, I derimmed it.
Let me tell you, the glass underneath? Beautiful. The smoothest glass edges.
COVERED in silicone.
The rim was so difficult to get off, my husband just basically ripped it apart. It would not wiggle off, because it was so solidly siliconed down. I don't know how he did it, but he did it.
I'm setting up my tank tomorrow once I spend like four more hours peeling silicone off. I'll do a journal when I do, then you all can see.