Being particularly selective with which fish to be showcased is just the icing on the cake. What most fascinates me with aquariums is the atmosphere and scenery itself. I've been brainstorming my next tank build and my days of being an OTR semi truck driver I have a room in my house that nicely fits a 4ft lenght by 6ft tall tank and I would like to base the theme on my days traveling through the rockies... giant Portland cement mountain, sand waterfall incorporated in, trees, winding road with scaled toy semi trucks... then I thought maybe a train track, bridges... then it hit me if I'd like to see a train in the scenery I should have a working train!!! What a great idea the love and details of train enthusiasm and aquariums together! So right off the bat what's wrong with that picture??? Electrical components and water... right? So here's the kicker... imagine an acrylic tunnel if you will, rectangle base track sits on with half cylinder tube sealed over the track, or maybe a 90 degree quarter cylinder for the side of the mountain track and all the wiring and terminals on the side of the tank with two tunnels leading out and into the aquarium. Figuring out glass thickness is relatively easy on a calculated form you know how thick should my tank be. My question is determining thickness of the acrylic tunnels inside the tank? Do I just assume half inch thick because that's what the chart says for 360 gallons or how can I calculate the pressure of water at different heights to determine glass thickness?