Also how thick acrylic should I get and is it something I could just get like at home depot or do I need to go somewhere where they might offer a higher grade of acrylic??? Also about the nylon bolts??
Sometimes those plastic companies will also sell some of their scrap for very cheap. All you need is a window so I bet there would be something you could use in the scrap bin. I think Lowes carries some nylon bolts and nuts but don't know how big they get. Personally I'd go with the 1/4" acrylic for the window
And as a sealant instead of using silicone, try and find a tube of Dow Corning 795. It is what the big glass tank builders like LeeMar use for their aquarium construction and is one of the only commercial adhesives that will glue acrylic to glass.
Sorry I am catching up here...this is a holding/mixing tank for new water with a "window"? Or is this some part of the system? ...Apologies for my confusion.
I really have no idea. In fact, I never thought about it. I'd be worried about getting moisture inside and then not be able to use the window for all the condensation.
Why not just use top lighting? I just use a old FW hood with a PC bulb above the 55 drum and can see fine. It's pretty dim but I'm not trying to grow any corals in there or anything.