I want to build a custom indoor pond for preds, with glass viewing panels, measurements aren't final, but I've been told you can go as far wide and back as you want let's say with 2-foot depth & you'll be fine with 12-15mm glass, but I want to go taller. I've been told 3-foot height maybe 18mm would be fine, but what if I go 4 foot or even 5 foot? how thick will I have to go? I'm open to the idea of bracing the glass with steel, also the idea that the pond could be 5 foot deep but have 2, 2-foot tall glass panels, or have 1 3 foot tall panel 1 foot off the bottom and 1 foot from the top. Let's say its 16x6x5 for example. I've been told 20, 25, 2 x 15, etc but im open to hear what you have to say, I've looked at charts but theyre all for generally sized aquariums, not custom-built whacky dimension aquariums. I've generally been told to go for glass but maybe there is a cheaper alternative? or a better alternative like acrylic which might work better but have a higher price tag or require less thickness?