I finally got around to getting the glass plates to cover up the closed loop holes in. Installing them was the easiest part, prepping the areas took the most time. The previous owner installed sch40 bulkheads in sh80 holes and used silicone to fill the gaps. It made it a real challenge to get the bulkheads out.
First step was to clean up the tank and get rid of loose sand.
There are a total of 6 holes. One large one for a 3" bulkhead and five for 2" bulkheads.
I used razor blades, steel wool, acetone, and dust free towels to make sure the glass was absolutely clean. Any debris is on the other side of the glass...
I have to give Glass Cages credit where credit is due. After getting a $500 quote from one local supplier and another local supplier getting angry with me that I couldn't use half inch glass I turned to glass cages. They were very polite, had a quote to me in an hour, and shipped the glass within 2 hours. I ordered it Friday at 2pm their time and had it on Tuesday! It cost around $160 shipped. The glass has good edges and was packaged really well.
I used a single bead of Momentive RTV108 about 1" from the edge of the plate and pressed them in place. I'll go back in a couple weeks and put a bead around the edges. I don't think it's necessary but will probably still do it.